Endocrine precursor cells, pancreatic hormone-expressing cells and methods of production

ABSTRACT

Disclosed herein are cell cultures and enriched cell populations of endocrine precursor cells, immature pancreatic hormone-expressing cells and mature pancreatic hormone-expressing cells. Also disclosed herein are methods of producing such cell cultures and cell populations.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/681,687, now U.S. Pat. No. 8,129,182, entitled ENDOCRINE PRECURSORCELLS, PANCREATIC HORMONE-EXPRESSING CELLS AND METHODS OF PRODUCTION,filed Mar. 2, 2007, which claims priority under 35 U.S.C. §119(e) toU.S. Provisional Patent Application No. 60/852,878, entitled ENRICHMENTOF ENDOCRINE PRECURSOR CELLS, IMMATURE PANCREATIC ISLET CELLS AND MATUREPANCREATIC ISLET CELLS USING NCAM, filed Oct. 18, 2006, and which claimspriority under 35 U.S.C. §119(e) to U.S. Provisional Patent ApplicationNo. 60/833,633, entitled INSULIN-PRODUCING CELLS AND METHOD OFPRODUCTION, filed Jul. 26, 2006, and which claims priority under 35U.S.C. §119(e) to U.S. Provisional Patent Application No. 60/778,649,entitled INSULIN-PRODUCING CELLS AND METHOD OF PRODUCTION, filed Mar. 2,2006. The disclosure of each of the above-listed priority applicationsis incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to the fields of medicine and cellbiology. In particular, the present invention relates to compositionscomprising mammalian endocrine precursor cells and compositionscomprising pancreatic hormone-expressing cells as well as methods ofmaking and using such cells.

BACKGROUND

Human embryonic stem cells (hESCs) have the potential to producedifferentiated cell types comprising all human somatic tissues andorgans. Of paramount importance for cell therapy treatment of insulindependent diabetes is the production of unlimited numbers of pancreaticendocrine cells that function similarly to islets with respect toglucose stimulated insulin release. Accordingly, there is need forglucose responsive-insulin producing cells derived from human embryonicstem cells in vitro as well as reliable methods for producing suchcells.

SUMMARY OF THE INVENTION

Some embodiments of the present invention relate to compositions, suchas cell cultures, comprising human pancreatic islet hormone-expressingcells. In such embodiments, the amount of human pancreatic islethormone-expressing cells can range from about 2% to about 80% of thehuman cells present in the cell culture. In some embodiments of thepresent invention, the pancreatic islet hormone-expressing cells can beeither mature pancreatic islet hormone-expressing cells, immaturepancreatic islet hormone-expressing cells or combinations of mature andimmature pancreatic islet hormone-expressing cells. In certainembodiments, the human pancreatic islet hormone-expressing cells expressone or more hormones selected from the group consisting of ghrelin,insulin, somatostatin and glucagon. In some embodiments, the islethormone-expressing cells express insulin in response to glucosestimulation.

Other embodiments relate to cell cultures comprising both humanpancreatic islet hormone-expressing cells and human endocrine precursorcells. In such embodiments, the amount of human endocrine precursorcells can range from about 5% to about 80% of the cells present in thecell culture. In some embodiments, the cell cultures comprisepredominately immature pancreatic islet hormone-expressing cells andendocrine precursor cells. In other embodiments, the cell culturescomprise both mature and immature pancreatic islet hormone-expressingcells as well as endocrine precursor cells.

Some embodiments described herein include compositions, such as cellcultures, comprising human endocrine precursor cells but which do notinclude a substantial amount of human pancreatic islethormone-expressing cells. In such embodiments, the amount of humanendocrine precursor cells can range from about 5% to about 80% of thehuman cells present in the cell culture. In certain embodiments, thehuman endocrine precursor cells express a marker selected from the groupconsisting of neurogenin 3 (NEUROG3 or NGN3) paired box 4 (PAX4) andNKX2 transcription factor related locus 2 (NKX2.2).

Other embodiments relate to cell cultures comprising both humanendocrine precursor cells and human PDX1-positive pancreatic endodermcells (PDX1-positive foregut endoderm cells), wherein the PDX1-positivepancreatic endoderm cells are PDX1-expressing, multipotent cells thatcan differentiate into cells, tissues or organs derived from theanterior portion of the gut tube. In such embodiments, the humanendocrine precursor cells can range from about 5% to about 95% of thecells present in said cell culture. In some embodiments, the amount ofhuman PDX1-positive pancreatic endoderm cells can range from about 5% toabout 95% of the cells present in said cell culture.

Still further embodiments of the present invention relate to methods ofproducing human mature pancreatic islet hormone-expressing cells, humanimmature pancreatic islet hormone-expressing cells, and human endocrineprecursor cells. In some embodiments, human mature pancreatic islethormone-expressing cells are produced from human immature pancreaticislet hormone-expressing cells. In some embodiments, human immaturepancreatic islet hormone-expressing cells are produced from humanendocrine precursor cells. In some embodiments, human endocrineprecursor cells are produced from human PDX1-positive pancreaticendoderm cells.

Other embodiments of the present invention relate to methods forproducing human pancreatic islet hormone-expressing cells from humanembryonic stem cells (hESCs) or other human pluripotent cells. In suchembodiments, the hESCs or other human pluripotent cells are firstdifferentiated to human definitive endoderm cells. Definitive endodermcells are multipotent cells that can differentiate into cells of the guttube or organs derived therefrom. Human definitive endoderm cells andtheir production have been described in U.S. patent application Ser. No.11/021,618, filed Dec. 23, 2004, the disclosure of which is incorporatedby reference in its entirety. The definitive endoderm cells are thendifferentiated to foregut endoderm. Human foregut endoderm cells aremultipotent cells that can differentiate into cells, tissues or organsderived from the anterior portion of the gut tube. Foregut endodermcells and their production have been described in U.S. ProvisionalPatent Application No. 60/730,917, filed Oct. 27, 2005, the disclosureof which is incorporated by reference in its entirety. The foregutendoderm cells are then differentiated to PDX1-positive pancreaticendoderm cells (PDX1-positive foregut endoderm). Human PDX1-positivepancreatic endoderm cells are multipotent cells that can differentiateinto cells, tissues or organs derived from the anterior portion of thegut tube. PDX1-positive pancreatic endoderm cells and their productionhave been described in U.S. patent application Ser. No. 11/115,868,filed Apr. 26, 2005 and U.S. Provisional Patent Application No.60/730,917, filed Oct. 27, 2005, the disclosures of which areincorporated herein by reference in their entireties. The PDX1-positivepancreatic endoderm cells are differentiated into endocrine precursorcells, which are differentiated into immature, and then finally mature,pancreatic islet hormone-expressing cells as described in U.S.Provisional Patent Application No. 60/833,633, filed Jul. 26, 2006, thedisclosure of which is incorporated herein by reference in its entirety,as well as the methods described herein.

Other embodiments described herein relate to methods of producing cellpopulations enriched in human endocrine precursor cells and methods ofproducing cell populations enriched in human immature pancreatic islethormone-expressing cells. In some embodiments, methods of producing cellpopulations enriched in endocrine precursor cells involves providing acell population that comprises human endocrine precursor cells with areagent that binds to neural cell adhesion molecule (NCAM), andseparating human endocrine precursor cells bound to the reagent fromcells that are not bound to the reagent. Similarly, in some embodiments,methods of producing cell populations enriched in human immaturepancreatic islet hormone-expressing cells involves providing a cellpopulation that comprises human immature pancreatic islethormone-expressing cells with a reagent that binds to NCAM, andseparating human immature pancreatic islet hormone-expressing cellsbound to the reagent from cells that are not bound to the reagent. Insome embodiments, additional enrichment of immature pancreatic islethormone-expressing cells can be achieved by contacting the NCAM-positivecell population with a second reagent that binds to CD133, and thenremoving from the cell population cells that are bound to the secondreagent.

In some embodiments of the present invention, the cell populationscomprising human pancreatic islet hormone-expressing cells produced bythe methods described herein can be derived from human endocrineprecursor cells. In certain embodiments of the methods of producing cellpopulations enriched for human endocrine precursor cells, the endocrineprecursor cells can be derived from human PDX1-positive pancreaticendoderm cells. In still further embodiments, the human PDX1-positivepancreatic endoderm cells are derived from human foregut endoderm cells.In yet further embodiments, the human foregut endoderm cells are derivedfrom human definitive endoderm cells. In still further embodiments, thehuman definitive endoderm cells are derived from human embryonic stemcells.

Other embodiments of the present invention relate to cell populationsthat are enriched for human endocrine precursor cells. In certainembodiments, the cell populations enriched for human endocrine precursorcells comprise from about 5% human endocrine precursor cells thatexpress Neurogenin 3 (NGN3), but that do not substantially express amarker selected from the group consisting of AFP, SOX7, SOX1, ZIC1, NFM,INS, GCG, SST and GHRL. In some embodiments, the cell populations thatare enriched for human endocrine precursor cells are obtained using themethods described herein for the production of cell populations enrichedfor human endocrine precursor cells.

Still other embodiments of the present invention relate to cellpopulations that are enriched for human immature pancreatic islethormone-expressing cells. The enriched cell populations can be obtainedby the methods described herein, comprising providing cell populationscomprising immature pancreatic islet hormone-expressing cells with areagent that binds NCAM, and separating the cells bound to said reagentfrom cells that are not bound to the reagent. In certain embodiments,the cell populations comprise at least about 25% to at least about 90%immature pancreatic hormone-expressing cells that express MAFB but donot substantially express MAFA and/or NGN3. In some embodiments, theenriched cell population comprises at least about 50% immaturepancreatic islet hormone-expressing cells that express MAFB but do notsubstantially express MAFA and/or NGN3.

Yet other embodiments of the present invention relate to cellpopulations that are enriched in human mature pancreatic islethormone-expressing cells that are derived in vitro from humanpluripotent cells. The enriched cell populations can be obtained by themethods described herein, such as by providing cell populationscomprising pancreatic islet hormone-expressing cells, which are producedin vitro from human pluripotent cells, with a reagent that binds NCAMand separating the cells bound to said reagent from cells that are notbound to the reagent. In certain embodiments, the cell populationscomprise at least about 25% to at least about 90% pancreatichormone-expressing cells that express at least one marker selected fromthe group consisting of GHRL, IAPP, INS, GCG, NKX6.1, SST and PP butwhich do not substantially express at least one marker selected from thegroup consisting of AFP, SOX7, SOX1, ZIC and NFM. In some embodiments,the enriched cell population comprises at least about 50% immaturepancreatic islet hormone-expressing cells that express GHRL, IAPP, INS,GCG, NKX6.1, SST and PP but not substantially express at least onemarker selected from the group consisting of AFP, SOX7, SOX1, ZIC andNFM.

Additional embodiments of the present invention relate to ex-vivoreagent-cell complexes comprising an NCAM binding reagent and a humanendocrine precursor cell that expresses NCAM, a human immaturepancreatic islet hormone-expressing cell that expresses NCAM or a humanmature pancreatic islet hormone-expressing cell that expresses NCAM. Incertain embodiments, the endocrine precursor cells, the immaturepancreatic islet hormone-expressing cells and/or the mature pancreaticislet hormone-expressing cells are derived in vitro from humanpluripotent cells. The reagent of the reagent-cell complexes cancomprise a molecule such as an anti-NCAM antibody, and anti-NCAMantibody fragment, or an NCAM ligand.

Other aspects of the present invention relate to in vitro cell culturesand in vitro cell populations as set forth herein that have not beendifferentiated in the presence of sodium butyrate or other histonedeacetylase inhibitor during any stage of their development. Otheraspects included herein relate to methods of producing endocrineprecursor cell cultures or cell populations and/or pancreatichormone-expressing cell cultures or cell populations in the absence ofsodium butyrate or other histone deacetylase inhibitor. In such aspects,hESCs are differentiated to definitive endoderm cells as well as celltypes derived from definitive endoderm, such as endocrine precursorcells and pancreatic hormone-expressing cells, in the absence of sodiumbutyrate or other histone deacetylase inhibitor.

Still other aspects of the present invention relate to cell cultures andcell populations comprising non-recombinant or non-engineered humanendocrine precursor cells and/or human pancreatic hormone-expressingcells. In some embodiments, the non-recombinant human endocrineprecursor cells and/or human pancreatic hormone-expressing cells of thecell cultures and/or cell populations are differentiated fromnon-recombinant hESCs. In some embodiments, non-recombinant hESCs aredifferentiated to definitive endoderm cells as well as cell typesderived from definitive endoderm, such as endocrine precursor cells andpancreatic hormone-expressing cells.

In certain jurisdictions, there may not be any generally accepteddefinition of the term “comprising.” As used herein, the term“comprising” is intended to represent “open” language which permits theinclusion of any additional elements. With this in mind, additionalembodiments of the present inventions are described with reference tothe numbered paragraphs below:

1. An in vitro cell culture comprising human cells wherein at leastabout 2% of said human cells are pancreatic islet hormone-expressingcells that express at least one pancreatic hormone selected from thegroup consisting of ghrelin, insulin, somatostatin and glucagon, saidpancreatic islet hormone-expressing cells being derived in vitro fromhuman pluripotent cells.

2. The in vitro cell culture of paragraph 1, wherein at least about 5%of said human cells are pancreatic islet hormone-expressing cells.

3. The in vitro cell culture of paragraph 1, wherein at least about 10%of said human cells are pancreatic islet hormone-expressing cells.

4. The in vitro cell culture of any of paragraphs 1 to 3, wherein atleast about 10% of said human cells are human endocrine precursor cellsthat express neurogenin 3 (NEUROG3).

5. The in vitro cell culture of paragraph 4, wherein said humanendocrine precursor cells express a marker selected from the groupconsisting of paired box 4 (PAX4) and NKX2 transcription factor relatedlocus 2 (NKX2.2).

6. The in vitro cell culture of any of paragraphs 1 to 3, wherein atleast about 50% of said human cells are human endocrine precursor cellsthat express neurogenin 3 (NEUROG3).

7. The in vitro cell culture of paragraph 6, wherein said humanendocrine precursor cells express a marker selected from the groupconsisting of paired box 4 (PAX4) and NKX2 transcription factor relatedlocus 2 (NKX2.2).

8. The in vitro cell culture of paragraph 1, wherein said pancreaticislet hormone-expressing cells express at least two hormones selectedfrom the group consisting of ghrelin, insulin, somatostatin andglucagon.

9. The in vitro cell culture of paragraph 1, wherein said pancreaticislet hormone-expressing cells express ghrelin, insulin, somatostatinand glucagon.

10. The in vitro cell culture of paragraph 1, wherein at least about 5%of the pancreatic islet hormone-expressing cells express insulin but donot significantly express ghrelin, somatostatin and glucagon.

11. The in vitro cell culture of paragraph 1, wherein at least about 10%of the pancreatic islet hormone-expressing cells express insulin but donot significantly express ghrelin, somatostatin and glucagon.

12. The in vitro cell culture of paragraph 1, wherein at least about 20%of the pancreatic islet hormone-expressing cells express insulin but donot significantly express ghrelin, somatostatin and glucagon.

13. The in vitro cell culture of paragraph 1, wherein at least about 30%of the pancreatic islet hormone-expressing cells express insulin but donot significantly express ghrelin, somatostatin and glucagon.

14. The in vitro cell culture of any one of paragraphs 10 to 13, whereininsulin is secreted in response to glucose stimulation.

15. The in vitro cell culture of any one of paragraphs 10 to 13, whereinC-peptide is secreted in response to glucose stimulation.

16. The in vitro cell culture of paragraph 1, wherein at said least 10%of said pancreatic islet cells are present in islet cell clusters.

17. The in vitro cell culture of paragraph 1, wherein said pancreaticislet hormone-expressing cells further express a marker selected fromthe group consisting of pancreatic duodenal homeobox 1 (PDX1), isletamyloid polypeptide (IAPP), pancreatic polypeptide (PP), ISL1transcription factor (ISL1), NKX6 transcription factor related locus 1(NKX6.1) and paired box 6 (PAX6).

18. The in vitro cell culture of paragraph 17, wherein said pancreaticislet hormone-expressing cells do not substantially express a markerselected from the group consisting of neurogenin 3 (NEUROG3) and pairedbox gene 4 (PAX4).

19. The in vitro cell culture of paragraph 1, wherein at least about 1pancreatic islet hormone-expressing cell is present for about every 10endocrine precursor cells in said cell culture.

20. The in vitro cell culture of paragraph 1, wherein at least about 1pancreatic islet hormone-expressing cell is present for about every 5endocrine precursor cells in said cell culture.

21. The in vitro cell culture of paragraph 1, wherein at least about 1pancreatic islet hormone-expressing cell is present for about every 2endocrine precursor cells in said cell culture.

22. The in vitro cell culture of paragraph 1, wherein said pancreaticislet hormone-expressing cells are non-recombinant cells.

23. The in vitro cell culture of paragraph 1 further comprising a mediumwhich comprises a factor selected from the group consisting ofnicotinamide (NIC), exendin 4 (Ex4), hepatocyte growth factor (HGF),insulin-like growth factor (IGF) and combinations thereof.

24. The in vitro cell culture of paragraph 1, further comprising amedium which comprises a factor selected from the group consisting ofexendin 4 (Ex4), hepatocyte growth factor (HGF), insulin-like growthfactor 1 (IGF1) and combinations thereof.

25. The in vitro cell culture of paragraph 1, further comprising amedium which comprises nicotinamide (NIC) at a concentration of about 10mM.

26. The in vitro cell culture of paragraph 1, further comprising amedium which comprises exendin 4 (Ex4) at a concentration of about 40ng/ml.

27. The in vitro cell culture of paragraph 1, further comprising amedium which comprises hepatocyte growth factor (HGF) at a concentrationof about 25 ng/ml.

28. The in vitro cell culture of paragraph 1, further comprising amedium which comprises insulin-like growth factor 1 (IGF1) at aconcentration of about 50 ng/ml.

29. An in vitro cell culture comprising human cells wherein at leastabout 5% of said human cells are endocrine precursor cells that expressneurogenin 3 (NEUROG3), said endocrine precursor cells being multipotentcells that can differentiate into pancreatic islet hormone-expressingcells that express at least one pancreatic hormone selected from thegroup consisting of insulin, somatostatin and glucagon.

30. The in vitro cell culture of paragraph 29, wherein at least about10% of said human cells are endocrine precursor cells.

31. The in vitro cell culture of paragraph 29, wherein at least about25% of said human cells are endocrine precursor cells.

32. The in vitro cell culture of paragraph 29, wherein at least about50% of said human cells are endocrine precursor cells.

33. The in vitro cell culture of any of paragraphs 29 to 32, wherein atleast about 10% of said human cells are human pancreatic duodenalhomeobox 1 (PDX1)-positive pancreatic endoderm cells.

34. The in vitro cell culture of any of paragraphs 29 to 32, wherein atleast about 25% of said human cells are human pancreatic duodenalhomeobox 1 (PDX1)-positive pancreatic endoderm cells.

35. The in vitro cell culture of any of paragraphs 29 to 32, wherein atleast about 50% of said human cells are human pancreatic duodenalhomeobox 1 (PDX1)-positive pancreatic endoderm cells.

36. The in vitro cell culture of any of paragraphs 29 to 32, whereinsaid cell culture is substantially devoid of human pancreatic islethormone-expressing cells.

37. The in vitro cell culture of paragraph 36, wherein at least about10% of said human cells are human pancreatic duodenal homeobox 1(PDX1)-positive pancreatic endoderm cells.

38. The in vitro cell culture of paragraph 36, wherein at least about25% of said human cells are human pancreatic duodenal homeobox 1(PDX1)-positive pancreatic endoderm cells.

39. The in vitro cell culture of paragraph 36, wherein at least about50% of said human cells are human pancreatic duodenal homeobox 1(PDX1)-positive pancreatic endoderm cells.

40. The in vitro cell culture of paragraph 29, wherein said endocrineprecursor cells express a marker selected from the group consisting ofpaired box 4 (PAX4) and NKX2 transcription factor related locus 2(NKX2.2).

41. The in vitro cell culture of paragraph 29, wherein at least about 1endocrine precursor cell is present for about every 10 PDX1-positivepancreatic endoderm cells in said cell culture.

42. The in vitro cell culture of paragraph 29, wherein at least about 1endocrine precursor cell is present for about every 5 PDX1-positivepancreatic endoderm cells in said cell culture.

43. The in vitro cell culture of paragraph 29, wherein at least about 1endocrine precursor cell is present for about every 2 PDX1-positivepancreatic endoderm cells in said cell culture.

44. The in vitro cell culture of paragraph 29, wherein said endocrineprecursor cells are non-recombinant cells.

45. The in vitro cell culture of paragraph 29 further comprising amedium which comprisesN—[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester(DAPT).

46. The in vitro cell culture of paragraph 45, wherein said DAPTconcentration is at least about 1 μM.

47. The in vitro cell culture of paragraph 45, wherein said DAPTconcentration is about 3 μM.

48. The in vitro cell culture of paragraph 45 further comprising afactor selected from retinoic acid (RA) and exendin 4 (Ex4).

49. The in vitro cell culture of paragraph 45, wherein said medium isCMRL.

50. A method of producing human pancreatic islet hormone-expressingcells, said method comprising the steps of obtaining a cell populationcomprising human endocrine precursor cells, said human endocrineprecursor cells being multipotent cells that can differentiate intohuman pancreatic islet hormone-expressing cells; and incubating saidhuman endocrine precursor cells in a culture medium for a sufficienttime to permit human pancreatic islet hormone-expressing cells to form,wherein said sufficient time for human pancreatic islethormone-expressing cells to form has been determined by detecting thepresence of human pancreatic islet hormone-expressing cells in said cellpopulation.

51. The method of paragraph 50, wherein at least about 2% of said humancells in said cell population differentiate into human pancreatic islethormone-expressing cells.

52. The method of paragraph 50, wherein at least about 5% of said humancells in said cell population differentiate into human pancreatic islethormone-expressing cells.

53. The method of paragraph 50, wherein at least about 10% of said humancells in said cell population differentiate into human pancreatic islethormone-expressing cells.

54. The method of paragraph 50 further comprising providing said humanpancreatic endocrine cells with a factor selected from the groupconsisting of nicotinamide (NIC), exendin 4 (Ex4), hepatocyte growthfactor (HGF), insulin-like growth factor-1 (IGF1) and combinationsthereof in an amount sufficient to further promote differentiation ofsaid human endocrine precursor cells to human pancreatic islethormone-expressing cells, wherein said human pancreatic islethormone-expressing cells express at least one pancreatic hormoneselected from the group consisting of insulin, somatostatin andglucagon.

55. The method of paragraph 54, wherein said factor is selected from thegroup consisting of Ex4, HGF and IGF1.

56. The method of paragraph 54, wherein Ex4 is provided to said cellpopulation of endocrine precursor cells at a concentration ranging fromabout 10 ng/ml to about 100 ng/ml.

57. The method of paragraph 54, wherein Ex4 is provided to said cellpopulation of endocrine precursor cells at a concentration of about 40ng/ml.

58. The method of paragraph 54, wherein said factor is IGF1.

59. The method of paragraph 58, wherein IGF1 is provided to said cellpopulation of endocrine precursor cells at a concentration ranging fromabout 10 ng/ml to about 1000 ng/ml.

60. The method of paragraph 58, wherein IGF1 is provided to said cellpopulation of endocrine precursor cells at a concentration ranging fromabout 10 ng/ml to about 100 ng/ml.

61. The method of paragraph 58, wherein IGF1 is provided to said cellpopulation of endocrine precursor cells at a concentration ranging fromabout 25 ng/ml to about 75 ng/ml.

62. The method of paragraph 58, wherein IGF1 is provided to said cellpopulation of endocrine precursor cells at a concentration of about 50ng/ml.

63. The method of paragraph 50, wherein detecting the presence of humanpancreatic islet hormone-expressing cells in said cell populationcomprises detecting the expression of at least one marker selected fromthe group consisting of pancreatic duodenal homeobox 1 (PDX1), ghrelin(GHRL), islet amyloid polypeptide (IAPP), pancreatic polypeptide (PP),ISL1 transcription factor (ISL1), NKX6 transcription factor relatedlocus 1 (NKX6.1) and paired box 6 (PAX6) in cells of said cellpopulation.

64. The method of paragraph 63, wherein the expression of at least oneof said markers is determined by Q-PCR.

65. The method of paragraph 63, wherein the expression of at least oneof said markers is determined by immunocytochemistry.

66. The method of paragraph 50, wherein the step of obtaining a cellpopulation comprising human endocrine precursor cells comprises thesteps of obtaining a population of human PDX1-positive pancreaticendoderm cells, said human PDX1-positive pancreatic endoderm cells beingmultipotent cells that can differentiate into cells, tissues or organsderived from the anterior portion of the gut tube; and providing saidpopulation of human PDX1-positive pancreatic endoderm cells with a gammasecretase inhibitor, thereby producing a population of human endocrineprecursor cells.

67. The method of paragraph 66, wherein said gamma secretase inhibitorcomprises N—[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycinet-butyl ester (DAPT).

68. The method of paragraph 67, wherein DAPT is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration ranging from about 1 μM to about 10 μM.

69. The method of paragraph 67, wherein DAPT is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration of about 3 μM.

70. The method of paragraph 66 further comprising providing saidpopulation of human PDX1-positive pancreatic endoderm cells with exendin4 (Ex4).

71. The method of paragraph 70, wherein Ex4 is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration ranging from about 10 ng/ml to about 100 ng/ml.

72. The method of paragraph 70, wherein Ex4 is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration of about 40 ng/ml.

73. The method of paragraph 70, wherein the step of obtaining apopulation of human PDX1-positive pancreatic endoderm cells comprisesthe steps of obtaining a population of human foregut endoderm cells,said human foregut endoderm cells being PDX1-negative multipotent cellsthat can differentiate into cells, tissues or organs derived from theanterior portion of the gut tube; and providing said population of humanforegut endoderm cells with a retinoid, thereby producing a populationof human PDX1-positive pancreatic endoderm cells.

74. The method of paragraph 73, wherein said retinoid is retinoic acid(RA)

75. The method of paragraph 74, wherein RA is provided to saidpopulation of human foregut endoderm cells at a concentration rangingfrom about 1 nM to about 10 μM

76. The method of paragraph 73, wherein the step of obtaining apopulation of human foregut endoderm cells comprises the steps ofobtaining a population of human definitive endoderm cells, said humandefinitive endoderm cells being multipotent cells that can differentiateinto cells of the gut tube or organs derived therefrom; and providingsaid population of human definitive endoderm cells with fibroblastgrowth factor 10 (FGF-10) and a hedgehog pathway inhibitor, therebyproducing a population of human foregut endoderm cells.

77. The method of paragraph 76 further comprising withdrawing any growthfactor of the TGF-β superfamily that may be present in said populationof definitive endoderm cells.

78. The method of paragraph 77, wherein said growth factor of the TGF-βsuperfamily is selected from the group consisting of Nodal, activin A,activin B and combinations thereof.

79. The method of paragraph 77, wherein said growth factor of the TGF-βsuperfamily is activin A.

80. The method of paragraph 76, wherein said hedgehog inhibitorcomprises KAAD-cyclopamine.

81. The method of paragraph 80, wherein KAAD-cyclopamine is provided tosaid population of human definitive endoderm cells at a concentrationranging from about 0.01 μM to about 1 μM.

82. The method of paragraph 80, wherein KAAD-cyclopamine is provided tosaid population of human definitive endoderm cells at a concentration ofabout 0.2 μM.

83. The method of paragraph 76, wherein FGF-10 is provided to saidpopulation of human definitive endoderm cells at a concentration rangingfrom about 1 ng/ml to about 1000 ng/ml.

84. The method of paragraph 76, wherein FGF-10 is provided to saidpopulation of human definitive endoderm cells at a concentration rangingfrom about 10 ng/ml to about 100 ng/ml.

85. The method of paragraph 76, wherein FGF-10 is provided to saidpopulation of human definitive endoderm cells at a concentration ofabout 50 ng/ml.

86. The method of paragraph 76, wherein the step of obtaining apopulation of human definitive endoderm cells comprises the steps ofobtaining a population of pluripotent human embryonic stem cells; andproviding said population of pluripotent human embryonic stem cells withat least one growth factor of the TGF-β superfamily.

87. The method of paragraph 86, wherein said at least one growth factoris Nodal.

88. The method of paragraph 86, wherein said at least one growth factoris activin A.

89. The method of paragraph 86, wherein said at least one growth factoris activin B.

90. The method of paragraph 86 further comprising providing saidpopulation of pluripotent human embryonic stem cells with wingless-typeMMTV integration site family member 3A (Wnt3A).

91. The method of paragraph 86, wherein a plurality of growth factors ofthe TGFβ superfamily is provided.

92. The method of paragraph 91, wherein Wnt3A is also provided.

93. The method of paragraph 86, wherein said at least one growth factoris provided in a concentration of at least about 10 ng/ml.

94. The method of paragraph 86, wherein said at least one growth factoris provided in a concentration of at least about 100 ng/ml.

95. The method of paragraph 86, wherein said at least one growth factoris provided in a concentration of at least about 500 ng/ml.

96. The method of paragraph 86, wherein said at least one growth factoris provided in a concentration of at least about 1000 ng/ml.

97. The method of paragraph 86, wherein said at least one growth factoris provided in a concentration of at least about 5000 ng/ml.

98. The method of paragraph 86, wherein said pluripotent human embryonicstem cells are differentiated to human definitive endoderm cells in amedium comprising less than about 2% serum.

99. The method of paragraph 86, wherein said pluripotent human embryonicstem cells are derived from a tissue selected from the group consistingof the morula, the ICM of an embryo and the gonadal ridges of an embryo.

100. A human pancreatic islet hormone-expressing cell produced by themethod of paragraph 86.

101. A method of producing human pancreatic islet hormone-expressingcells, said method comprising the steps of: (a) obtaining a populationof pluripotent human embryonic stem cells; (b) providing said populationof pluripotent human embryonic stem cells with at least one growthfactor of the TGF-β superfamily, thereby producing a population of humandefinitive endoderm cells; (c) providing said population of humandefinitive endoderm cells with at least one fibroblast growth factor,thereby producing a population of human foregut endoderm cells; (d)providing said population of human foregut endoderm cells with aretinoid, thereby producing a population of human PDX1-positivepancreatic endoderm cells; (e) providing said population of humanPDX1-positive pancreatic endoderm cells with a gamma secretaseinhibitor, thereby producing a population comprising human endocrineprecursor cells; and (f) incubating said population of human endocrineprecursor cells in a culture medium for a sufficient time to permithuman pancreatic islet hormone-expressing cells to form.

102. The method of paragraph 101, wherein step (b) further comprisesproviding a hedgehog pathway inhibitor.

103. The method of paragraph 101, wherein said fibroblast growth factoris selected from the group consisting of FGF1, FGF2, FGF3, FGF4, FGF5,FGF6, FGF7, FGF8, FGF9, FGF10, FGF11, FGF12, FGF13, FGF14, FGF15, FGF16,FGF17, FGF18, FGF19, FGF20, FGF21, FGF22 and FGF23.

104. The method of paragraph 101, wherein said fibroblast growth factorcomprises FGF10.

105. The method of paragraph 101, wherein step (d) further comprisesproviding insulin or an insulin-like growth factor.

106. The method of paragraph 101 further comprising substantiallywithdrawing said at least one growth factor of the TGF-β superfamily.

107. The method of paragraph 101, wherein said retinoid and said gammasecretase are provided at about the same time.

108. The method of paragraph 101, wherein said foregut endoderm cellsare competent to further differentiate into pancreatic cells.

109. A method of producing human pancreatic islet hormone-expressingcells, said method comprising the steps of: (a) obtaining a populationof pluripotent human embryonic stem cells; (b) providing said populationof pluripotent human embryonic stem cells with at least one growthfactor of the TGF-β superfamily, thereby producing a population of humandefinitive endoderm cells; (c) providing said population of humandefinitive endoderm cells with a retinoid, thereby producing apopulation of human PDX1-positive pancreatic endoderm cells; and (d)incubating said population of human PDX1-positive pancreatic endodermcells in the presence of a retinoid for a sufficient time to permithuman pancreatic islet hormone-expressing cells to form.

110. The method of paragraph 109 further comprising the step ofproviding said population of human definitive endoderm cells with afibroblast family growth factor.

111. The method of paragraph 110, wherein said fibroblast family growthfactor comprises FGF10 or FGF7.

112. The method of paragraph 109, further comprising the step ofproviding said population of human definitive endoderm cells with ahedgehog pathway inhibitor.

113. The method of paragraph 112, wherein said hedgehog pathwayinhibitor is KAAD-cyclopamine.

114. The method of paragraph 109, wherein said retinoid is retinoicacid.

115. The method of paragraph 109, further comprising the step ofproviding said population of human PDX1-positive pancreatic endodermcells with a gamma secretase inhibitor.

116. The method of paragraph 115, wherein the gamma secretase inhibitorcomprises N—[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycinet-butyl ester (DAPT).

117. A method for producing a cell population enriched in humanendocrine precursor cells, said method comprising the steps of providinga cell population comprising human endocrine precursor cells with areagent that binds to neural cell adhesion molecule (NCAM), andseparating human endocrine precursor cells bound to said reagent fromcells that are not bound to said reagent, thereby producing a cellpopulation enriched in human endocrine precursor cells.

118. The method of paragraph 117, wherein said human endocrine precursorcells are derived in vitro from human pluripotent cells.

119. The method of paragraph 117, wherein said human endocrine precursorcells express Neurogenin 3 (NGN3) and do not substantially express atleast one marker selected from the group consisting of AFP, SOX7, SOX1,ZIC1, NFM, insulin (INS), glucagon (GCG), somatostatin (SST) and ghrelin(GHRL).

120. The method of paragraph 119, wherein said human endocrine precursorcells express paired box gene 4 (PAX4).

121. The method of paragraph 119, wherein said human endocrine precursorcells do not substantially express Paired Box 6 transcription factor(PAX6).

122. The method of paragraph 117, wherein said reagent comprises amolecule selected from the group consisting of an anti-NCAM antibody, ananti-NCAM antibody fragment and an NCAM ligand.

123. The method of paragraph 122, wherein said NCAM ligand is NCAMBinding Protein 10 (NBP10).

124. The method of paragraph 122, wherein said anti-NCAM antibody islabeled.

125. The method of paragraph 124, wherein said anti-NCAM antibody isfluorescently labeled.

126. The method of paragraph 117 further comprising providing said cellpopulation and said reagent with a secondary reagent that binds to saidreagent.

127. The method of paragraph 126, wherein said reagent comprises andanti-NCAM antibody and wherein said secondary reagent is fluorescentlylabeled.

128. The method of paragraph 125 or paragraph 127, wherein saidseparating step comprises using fluorescence activated cell sorting(FACS) to separate said endocrine precursor cells bound to saidanti-NCAM antibodies from said cells that are not bound to saidanti-NCAM antibodies.

129. The method of paragraph 117 further comprising the step ofdisaggregating said cells in said cell population comprising humanendocrine precursor cells prior to providing said cell population withsaid reagent that binds to NCAM.

130. The method of paragraph 117 further comprising the steps ofobtaining a cell population comprising a population of humanPDX1-positive pancreatic endoderm cells, said human PDX1-positivepancreatic endoderm cells being multipotent cells that can differentiateinto cells, tissues or organs derived from the anterior portion of thegut tube and providing said population of human PDX1-positive pancreaticendoderm cells with a gamma secretase inhibitor, thereby producing apopulation of human endocrine precursor cells.

131. The method of paragraph 130, wherein said gamma secretase inhibitorcomprises N—[N-(3,5,-difluorophenacetyl)-L-alanyl]-S-phenylglycinet-butyl ester (DAPT).

132. The method of paragraph 131, wherein said DAPT is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration ranging from about 1 μM to about 10 μM.

133. The method of paragraph 131, wherein said DAPT is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration of about 3 μM.

134. The method of paragraph 130, further comprising providing saidpopulation of human PDX1-positive pancreatic endoderm cells with exendin4 (Ex4).

135. The method of paragraph 134, wherein said Ex4 is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration ranging from about 10 ng/ml to about 100 ng/ml.

136. The method of paragraph 134, wherein said Ex4 is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration of about 40 ng/ml.

137. The method of paragraph 130, wherein the step of obtaining apopulation of human PDX1-positive pancreatic endoderm cells comprisesthe steps of obtaining a population of human foregut endoderm cells,said human foregut endoderm cells being PDX1-negative multipotent cellsthat can differentiate into cells, tissues or organs derived from theanterior portion of the gut tube and providing said population of humanforegut endoderm cells with a retinoid, thereby producing a populationof human PDX1-positive pancreatic endoderm cells.

138. The method of paragraph 137, wherein said retinoid is retinoic acid(RA).

139. The method of paragraph 138, wherein RA is provided to saidpopulation of human foregut endoderm cells at a concentration rangingfrom about 1 nM to about 10 μM.

140. The method of paragraph 137, wherein the step of obtaining apopulation of human foregut endoderm cells comprises the steps ofobtaining a population of human definitive endoderm cells, said humandefinitive endoderm cells being multipotent cells that can differentiateinto cells of the gut tube or organs derived therefrom and providingsaid population of human definitive endoderm cells with fibroblastgrowth factor 10 (FGF-10) and a hedgehog pathway inhibitor, therebyproducing a population of human foregut endoderm cells.

141. The method of paragraph 140, further comprising withdrawing anexogenously added factor of the TGF-β superfamily that may be present insaid population of definitive endoderm cells.

142. The method of paragraph 141, wherein said growth factor of theTGF-β superfamily is selected from the group consisting of Nodal,activin A, activin B and combinations thereof.

143. The method of paragraph 142, wherein said growth factor of theTGF-β superfamily is activin A.

144. The method of paragraph 140, wherein said hedgehog inhibitorcomprises KAAD-cyclopamine.

145. The method of paragraph 144, wherein KAAD-cyclopamine is providedto said population of human definitive endoderm cells at a concentrationranging from about 0.01 μM to about 1 μM.

146. The method of paragraph 145, wherein KAAD-cyclopamine is providedto said population of human definitive endoderm cells at a concentrationof about 0.2 μM.

147. The method of paragraph 140, wherein FGF-10 is provided to saidpopulation of human definitive endoderm cells at a concentration rangingfrom about 10 ng/ml to about 1000 ng/ml.

148. The method of paragraph 140, wherein FGF-10 is provided to saidpopulation of human definitive endoderm cells at a concentration rangingfrom about 1 ng/ml to about 100 ng/ml.

149. The method of paragraph 140, wherein FGF-10 is provided to saidpopulation of human definitive endoderm cells at a concentration ofabout 50 ng/ml.

150. The method of paragraph 140, wherein the step of obtaining apopulation of human definitive endoderm cells comprises the steps ofobtaining a population of human pluripotent cells and providing saidpopulation of human pluripotent cells with at least one growth factor ofthe TGF-β superfamily.

151. The method of paragraph 150, wherein said at least one growthfactor is Nodal.

152. The method of paragraph 150, wherein said at least one growthfactor is activin A.

153. The method of paragraph 150, wherein said at least one growthfactor is activin B.

154. The method of paragraph 150 further comprising providing saidpopulation of human pluripotent cells with wingless-type MMTVintegration site family member 3A (Wnt3A).

155. The method of paragraph 150, wherein a plurality of growth factorsof the TGFβ superfamily is provided.

156. The method of paragraph 155, wherein Wnt3A is also provided.

157. The method of paragraph 150, wherein said at least one growthfactor is provided in a concentration of at least about 10 ng/ml.

158. The method of paragraph 150, wherein said at least one growthfactor is provided in a concentration of at least about 100 ng/ml.

159. The method of paragraph 150, wherein said at least one growthfactor is provided in a concentration of at least about 500 ng/ml.

160. The method of paragraph 150, wherein said at least one growthfactor is provided in a concentration of at least about 1000 ng/ml.

161. The method of paragraph 150, wherein said at least one growthfactor is provided in a concentration of at least about 5000 ng/ml.

162. The method of paragraph 150, wherein said human pluripotent cellsare differentiated to human definitive endoderm cells in a mediumcomprising less than about 2% serum.

163. The method of paragraph 150, wherein said human pluripotent cellsare human embryonic stem cells derived from a tissue selected from thegroup consisting of the morula, the ICM of an embryo and the gonadalridges of an embryo.

164. An enriched, in vitro human endocrine precursor cell population,wherein said human endocrine precursor cells express NGN3 and do notsubstantially express at least one marker selected from the groupconsisting of AFP, SOX7, SOX1, ZIC1, NFM, INS, GCG, SST and GHRL.

165. The enriched, in vitro human endocrine precursor cell population ofparagraph 164, wherein said cell population is derived in vitro fromhuman pluripotent cells.

166. The enriched, in vitro human endocrine precursor cell population ofparagraph 164, wherein said enriched human endocrine precursor cellpopulation is produced by the method of paragraph 117.

167. The enriched, in vitro human endocrine precursor cell population ofparagraph 164, wherein said enriched human endocrine precursor cellpopulation is produced by the method of paragraph 150.

168. The enriched, in vitro human endocrine precursor cell population ofparagraph 164, wherein at least about 5% of said enriched human cellpopulation comprises human endocrine precursor cells that expressneurogenin 3 (NGN3) and do not substantially express at least one markerselected from the group consisting of AFP, SOX7, SOX1, ZIC1 NFM, INS,GCG, SST and GHRL.

169. The enriched, in vitro human endocrine precursor cell population ofparagraph 168, wherein said human endocrine precursor cells expressPAX4.

170. The enriched, in vitro human endocrine precursor cell population ofparagraph 164, wherein said endocrine precursor cells are derived invitro from human PDX1-positive pancreatic endoderm.

171. The enriched, in vitro human endocrine precursor cell population ofparagraph 170, wherein said human PDX1-positive pancreatic endodermcells are derived in vitro from human foregut endoderm cells.

172. The enriched, in vitro human endocrine precursor cell population ofparagraph 171, wherein said human foregut endoderm cells are derived invitro from definitive endoderm cells.

173. The enriched, in vitro human endocrine precursor cell population ofparagraph 172, wherein said definitive endoderm cells are derived invitro from human embryonic stem cells (hESCs).

174. A method for producing a cell population enriched in human immaturepancreatic islet hormone-expressing cells, said method comprising thesteps of providing a cell population comprising human immaturepancreatic islet hormone-expressing cells with a reagent that binds toneural cell adhesion molecule (NCAM) and separating human immaturepancreatic islet hormone-expressing cells bound to said reagent fromcells that are not bound to said reagent, thereby producing a cellpopulation enriched in human immature pancreatic islethormone-expressing cells.

175. The method of paragraph 174, wherein said human immature pancreaticislet hormone-expressing cells are derived in vitro from humanpluripotent cells.

176. The method of paragraph 174, wherein said human immature pancreaticislet hormone-expressing cells express MAFB and do not substantiallyexpress a marker selected from the group consisting of NGN3 and MAFA.

177. The method of paragraph 176, wherein said human immature pancreaticislet hormone-expressing cells do not substantially express at least onemarker selected from the group consisting of MOX1, CER, POU5F1, AFP,SOX7, SOX1, ZIC1 and NFM.

178. The method of paragraph 176, wherein said human immature pancreaticislet hormone-expressing cells express at least one marker selected fromthe group consisting of Synaptophysin (SYP), Chromogranin A (CHGA),NKX2.2, Islet 1 (ISL1), Paired Box Gene 6 (PAX6), and NeurogenicDifferentiation 1 (NEUROD), PDX1 and HB9.

179. The method of paragraph 174, wherein said human immature pancreaticislet hormone-expressing cells process less than about 98% of theinsulin produced by said immature pancreatic islet hormone-expressingcells.

180. The method of paragraph 174, wherein said human immature pancreaticislet hormone-expressing cells process less than about 70% of theinsulin produced by said immature pancreatic islet hormone-expressingcells.

181. The method of paragraph 179 or paragraph 180, wherein said insulinprocessing is measured by C-peptide release.

182. The method of paragraph 174, wherein said reagent comprises amolecule selected from the group consisting of an anti-NCAM antibody, ananti-NCAM antibody fragment and an NCAM ligand.

183. The method of paragraph 182, wherein said NCAM ligand is NCAMBinding Protein 10 (NBP10).

184. The method of paragraph 182, wherein said anti-NCAM antibody islabeled.

185. The method of paragraph 184, wherein said anti-NCAM antibody isfluorescently labeled.

186. The method of paragraph 174, further comprising providing said cellpopulation with a secondary reagent that binds to said reagent.

187. The method of paragraph 186 wherein said reagent comprises andanti-NCAM antibody and wherein said secondary reagent that binds to saidanti-NCAM antibody is fluorescently labeled.

188. The method of paragraph 185 or paragraph 187, wherein saidseparating step comprises using fluorescence activated cell sorting(FACS) to separate said human immature pancreatic islethormone-expressing cells bound to said anti-NCAM antibody from saidcells that are not bound to said anti-NCAM antibody.

189. The method of paragraph 174 further comprising the step ofproviding said human immature pancreatic islet hormone-expressing cellswith a second reagent that binds to CD133, and separating said humanimmature pancreatic islet hormone-expressing cells from cells that arebound to said second reagent.

190. The method of paragraph 174 further comprising the step ofdissociating said cell population prior to providing said cellpopulation with said reagent that binds NCAM.

191. The method of paragraph 174 further comprising obtaining a cellpopulation comprising human endocrine precursor cells being multipotentcells that can differentiate into human immature pancreatic islethormone-expressing cells and incubating said human endocrine precursorcells in a culture medium for a sufficient time to permit human immaturepancreatic islet hormone-expressing cells to form.

192. The method of paragraph 191 further comprising providing said humanendocrine precursor cells with a factor selected from the groupconsisting of nicotinamide (NIC), exendin 4 (Ex4), hepatocyte growthfactor (HGF), insulin-like growth factor-1 (IGF1), glucose dependentinsulinotropic polypeptide (GIP), nerve growth factor (NGF), vascularendothelial growth factor (VEGF) and combinations thereof in an amountsufficient to further promote differentiation of said human endocrineprecursor cells to human immature pancreatic islet hormone-expressingcells.

193. The method of paragraph 192, wherein said factor is selected fromthe group consisting of Ex4, HGF and IGF1.

194. The method of paragraph 193, wherein said factor is Ex4.

195. The method of paragraph 194, wherein Ex4 is provided to said cellpopulation of endocrine precursor cells at a concentration ranging fromabout 10 ng/ml to about 100 ng/ml.

196. The method of paragraph 194, wherein Ex4 is provided to said cellpopulation of endocrine precursor cells at a concentration of about 40ng/ml.

197. The method of paragraph 193, wherein said factor is IGF1.

198. The method of paragraph 197, wherein IGF1 is provided to said cellpopulation of endocrine precursor cells at a concentration ranging fromabout 10 ng/ml to about 1000 ng/ml.

199. The method of paragraph 197, wherein IGF1 is provided to said cellpopulation of endocrine precursor cells at a concentration ranging fromabout 10 ng/ml to about 100 ng/ml.

200. The method of paragraph 197, wherein IGF1 is provided to said cellpopulation of endocrine precursor cells at a concentration ranging fromabout 25 ng/ml to about 75 ng/ml.

201. The method of paragraph 197, wherein IGF1 is provided to said cellpopulation of endocrine precursor cells at a concentration of about 50ng/ml.

202. The method of paragraph 191 further comprising the steps ofobtaining a cell population comprising a population of humanPDX1-positive pancreatic endoderm cells, said human PDX1-positivepancreatic endoderm cells being multipotent cells that can differentiateinto cells, tissues or organs derived from the anterior portion of thegut tube and providing said population of human PDX1-positive pancreaticendoderm cells with a gamma secretase inhibitor, thereby producing apopulation of human endocrine precursor cells.

203. The method of paragraph 202, wherein said gamma secretase inhibitorcomprises N—[N-(3,5,-difluorophenacetyl)-L-alanyl]-S-phenylglycinet-butyl ester (DAPT).

204. The method of paragraph 203, wherein said DAPT is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration ranging from about 1 μM to about 10 μM.

205. The method of paragraph 203, wherein said DAPT is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration of about 3 μM.

206. The method of paragraph 202, further comprising providing saidpopulation of human PDX1-positive pancreatic endoderm cells with exendin4 (Ex4).

207. The method of paragraph 206, wherein said Ex4 is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration ranging from about 10 ng/ml to about 100 ng/ml.

208. The method of paragraph 206, wherein said Ex4 is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration of about 40 ng/ml.

209. The method of paragraph 202, wherein the step of obtaining apopulation of human PDX1-positive pancreatic endoderm cells comprisesthe steps of obtaining a population of human foregut endoderm cells,said human foregut endoderm cells being PDX1-negative multipotent cellsthat can differentiate into cells, tissues or organs derived from theanterior portion of the gut tube and providing said population of humanforegut endoderm cells with a retinoid, thereby producing a populationof human PDX1-positive pancreatic endoderm cells.

210. The method of paragraph 209, wherein said retinoid is retinoic acid(RA).

211. The method of paragraph 210, wherein RA is provided to saidpopulation of human foregut endoderm cells at a concentration rangingfrom about 1 nM to about 10 μM.

212. The method of paragraph 209, wherein the step of obtaining apopulation of human foregut endoderm cells comprises the steps ofobtaining a population of human definitive endoderm cells, said humandefinitive endoderm cells being multipotent cells that can differentiateinto cells of the gut tube or organs derived therefrom and providingsaid population of human definitive endoderm cells with fibroblastgrowth factor 10 (FGF-10) and a hedgehog pathway inhibitor, therebyproducing a population of human foregut endoderm cells.

213. The method of paragraph 212 further comprising withdrawing anexogenously added factor of the TGF-βsuperfamily that may be present insaid population of definitive endoderm cells.

214. The method of paragraph 213, wherein said growth factor of theTGF-β superfamily is selected from the group consisting of Nodal,activin A, activin B and combinations thereof.

215. The method of paragraph 214, wherein said growth factor of theTGF-β superfamily is activin A.

216. The method of paragraph 212, wherein said hedgehog inhibitorcomprises KAAD-cyclopamine.

217. The method of paragraph 216, wherein KAAD-cyclopamine is providedto said population of human definitive endoderm cells at a concentrationranging from about 0.01 μM to about 1 μM.

218. The method of paragraph 216, wherein KAAD-cyclopamine is providedto said population of human definitive endoderm cells at a concentrationof about 0.2 μM.

219. The method of paragraph 212, wherein FGF-10 is provided to saidpopulation of human definitive endoderm cells at a concentration rangingfrom about 1 ng/ml to about 1000 ng/ml.

220. The method of paragraph 212, wherein FGF-10 is provided to saidpopulation of human definitive endoderm cells at a concentration rangingfrom about 10 ng/ml to about 100 ng/ml.

221. The method of paragraph 212, wherein FGF-10 is provided to saidpopulation of human definitive endoderm cells at a concentration ofabout 50 ng/ml.

222. The method of paragraph 212, wherein the step of obtaining apopulation of human definitive endoderm cells comprises the steps ofobtaining a population of human pluripotent cells and providing saidpopulation of human pluripotent cells with at least one growth factor ofthe TGF-β superfamily.

223. The method of paragraph 222, wherein said at least one growthfactor is Nodal.

224. The method of paragraph 222, wherein said at least one growthfactor is activin A.

225. The method of paragraph 222, wherein said at least one growthfactor is activin B.

226. The method of paragraph 222 further comprising providing saidpopulation of human pluripotent cells with wingless-type MMTVintegration site family member 3A (Wnt3A).

227. The method of paragraph 222, wherein a plurality of growth factorsof the TGFβ superfamily is provided.

228. The method of paragraph 227, wherein Wnt3A is also provided.

229. The method of paragraph 222, wherein said at least one growthfactor is provided in a concentration of at least about 10 ng/ml.

230. The method of paragraph 222, wherein said at least one growthfactor is provided in a concentration of at least about 100 ng/ml.

231. The method of paragraph 222, wherein said at least one growthfactor is provided in a concentration of at least about 500 ng/ml.

232. The method of paragraph 222, wherein said at least one growthfactor is provided in a concentration of at least about 1000 ng/ml.

233. The method of paragraph 222, wherein said at least one growthfactor is provided in a concentration of at least about 5000 ng/ml.

234. The method of paragraph 222, wherein said human pluripotent cellsare differentiated to human definitive endoderm cells in a mediumcomprising less than about 2% serum.

235. The method of paragraph 222, wherein said human pluripotent cellsare human embryonic stem cells derived from a tissue selected from thegroup consisting of the morula, the ICM of an embryo and the gonadalridges of an embryo.

236. An enriched, in vitro human immature pancreatic islethormone-expressing cell population, wherein said human immaturepancreatic islet hormone-expressing cells express MAFB and do notsubstantially express NGN3 and MAFA

237. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 236, wherein theenriched cell population is derived in vitro from human pluripotentcells.

238. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 236, wherein saidenriched cell population is produced by the method of paragraph 174.

239. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 236, wherein saidenriched cell population is produced by the method of paragraph 222.

240. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 238 or paragraph 239,wherein at least about 25% of said enriched human cell populationcomprises human immature pancreatic islet hormone-expressing cells thatexpress MAFB and do not substantially express NGN3 and MAFA.

241. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 238 or paragraph 239,wherein at least about 50% of said enriched human cell populationcomprises human immature pancreatic islet hormone-expressing cells thatexpress MAFB and do not substantially express NGN3 and MAFA.

242. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 238 or paragraph 239,wherein at least about 70% of said enriched human cell populationcomprises human immature pancreatic islet hormone-expressing cells thatexpress MAFB and do not substantially express NGN3 and MAFA.

243. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 238 or paragraph 239,wherein at least about 90% of said enriched human cell populationcomprises human immature pancreatic islet hormone-expressing cells thatexpress MAFB and do not substantially express NGN3 and MAFA.

244. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 236, wherein at leastabout 25% of said enriched human cell population comprises humanimmature pancreatic islet hormone-expressing cells that express MAFB anddo not substantially express NGN3 and MAFA.

245. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 236, wherein at leastabout 50% of said enriched human cell population comprises humanimmature pancreatic islet hormone-expressing cells that express MAFB anddo not substantially express NGN3 and MAFA.

246. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 236, wherein at leastabout 70% of said enriched human cell population comprises humanimmature pancreatic islet hormone-expressing cells that express MAFB anddo not substantially express NGN3 and MAFA.

247. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 236, wherein at leastabout 90% of said enriched human cell population comprises humanimmature pancreatic islet hormone-expressing cells that express MAFB anddo not substantially express NGN3 and MAFA.

248. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 236, wherein said humanimmature pancreatic islet hormone-expressing cells do not substantiallyexpress at least one marker selected from the group consisting ofelected from the group consisting of MOX1, CER, POU5F1, AFP, SOX7, SOX1,ZIC1 and NFM.

249. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 236, wherein said humanimmature pancreatic islet hormone-expressing cells express at least onemarker selected from the group consisting of Synaptophysin (SYP),Chromogranin A (CHGA), NKX2.2, Islet 1 (ISL1), Paired Box Gene 6 (PAX6),Neurogenic Differentiation 1 (NEUROD), PDX1 and HB9.

250. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 236, wherein said humanimmature pancreatic islet hormone-expressing cells process less thanabout 98% of the insulin produced by said immature pancreatic islethormone-expressing cells.

251. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 236, wherein said humanimmature pancreatic islet hormone-expressing cells process less thanabout 70% of the insulin produced by said immature pancreatic islethormone-expressing cells.

252. The enriched, in vitro human immature pancreatic islethormone-expressing cell population of paragraph 250 or paragraph 251,wherein said insulin processing is measured by C-peptide release.

253. A method for producing a cell population enriched in humanpancreatic islet hormone-expressing cells, said pancreatichormone-expressing cells being derived in vitro from human pluripotentcells, said method comprising the steps of providing a cell populationcomprising human pancreatic islet hormone-expressing cells with areagent that binds to neural cell adhesion molecule (NCAM) andseparating human endocrine precursor cells bound to said reagent fromcells that are not bound to said reagent, thereby producing a cellpopulation enriched in human pancreatic islet hormone-expressing cells.

254. The method of paragraph 253, wherein said reagent comprises amolecule selected from the group consisting of an anti-NCAM antibody, ananti-NCAM antibody fragment and an NCAM ligand.

255. The method of paragraph 254, wherein said NCAM ligand is NCAMBinding Protein 10 (NBP10).

256. The method of paragraph 254, wherein said anti-NCAM antibody islabeled.

257. The method of paragraph 256, wherein said anti-NCAM antibody isfluorescently labeled.

258. The method of paragraph 254 further comprising providing said cellpopulation with a secondary reagent that binds to said reagent.

259. The method of paragraph 258, wherein said reagent comprises andanti-NCAM antibody and wherein said secondary reagent that binds to saidanti-NCAM antibody is fluorescently labeled.

260. The method of paragraph 257 or paragraph 259, wherein saidseparating step comprises using fluorescence activated cell sorting(FACS) to separate said pancreatic islet hormone-expressing cells boundto said anti-NCAM antibody from said cells that are not bound to saidanti-NCAM antibody.

261. The method of paragraph 253 further comprising the step ofproviding said human immature pancreatic islet hormone-expressing cellswith a second reagent that binds to CD133, and separating said humanimmature pancreatic islet hormone-expressing cells from cells that arebound to said second reagent.

262. The method of paragraph 253 further comprising the step ofdissociating said cell population prior to providing said cellpopulation with said reagent that binds NCAM.

263. The method of paragraph 253 further comprising obtaining a cellpopulation comprising human endocrine precursor cells being multipotentcells that can differentiate into human pancreatic islethormone-expressing cells and incubating said human endocrine precursorcells in a culture medium for a sufficient time to permit humanpancreatic islet hormone-expressing cells to form.

264. The method of paragraph 263 further comprising providing said humanpancreatic endocrine cells with a factor selected from the groupconsisting of nicotinamide (NIC), exendin 4 (Ex4), hepatocyte growthfactor (HGF), insulin-like growth factor-1 (IGF1), glucose dependentinslulinotropic polypeptide (GIP), nerve growth factor (NGF), vascularendothelial growth factor (VEGF) and combinations thereof in an amountsufficient to further promote differentiation of said human endocrineprecursor cells to human pancreatic islet hormone-expressing cells,wherein said human pancreatic islet hormone-expressing cells express atleast one pancreatic hormone selected from the group consisting ofinsulin, somatostatin and glucagon.

265. The method of paragraph 264, wherein said factor is selected fromthe group consisting of Ex4, HGF and IGF1.

266. The method of paragraph 265, wherein said factor is Ex4.

267. The method of paragraph 266, wherein Ex4 is provided to said cellpopulation of endocrine precursor cells at a concentration ranging fromabout 10 ng/ml to about 100 ng/ml.

268. The method of paragraph 266, wherein Ex4 is provided to said cellpopulation of endocrine precursor cells at a concentration of about 40ng/ml.

269. The method of paragraph 265, wherein said factor is IGF 1.

270. The method of paragraph 269 wherein IGF1 is provided to said cellpopulation of endocrine precursor cells at a concentration ranging fromabout 10 ng/ml to about 1000 ng/ml.

271. The method of paragraph 269, wherein IGF1 is provided to said cellpopulation of endocrine precursor cells at a concentration ranging fromabout 10 ng/ml to about 100 ng/ml.

272. The method of paragraph 269, wherein IGF1 is provided to said cellpopulation of endocrine precursor cells at a concentration ranging fromabout 25 ng/ml to about 75 ng/ml.

273. The method of paragraph 269, wherein IGF1 is provided to said cellpopulation of endocrine precursor cells at a concentration of about 50ng/ml.

274. The method of paragraph 263 further comprising the steps ofobtaining a cell population comprising a population of humanPDX1-positive pancreatic endoderm cells, said human PDX1-positivepancreatic endoderm cells being multipotent cells that can differentiateinto cells, tissues or organs derived from the anterior portion of thegut tube and providing said population of human PDX1-positive pancreaticendoderm cells with a gamma secretase inhibitor, thereby producing apopulation of human endocrine precursor cells.

275. The method of paragraph 274, wherein said gamma secretase inhibitorcomprises N—[N-(3,5,-difluorophenacetyl)-L-alanyl]-S-phenylglycinet-butyl ester (DAPT).

276. The method of paragraph 275, wherein said DAPT is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration ranging from about 1 μM to about 10 μM.

277. The method of paragraph 275, wherein said DAPT is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration of about 3 μM.

278. The method of paragraph 274 further comprising providing saidpopulation of human PDX1-positive pancreatic endoderm cells with exendin4 (Ex4).

279. The method of paragraph 278, wherein said Ex4 is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration ranging from about 10 ng/ml to about 100 ng/ml.

280. The method of paragraph 278, wherein said Ex4 is provided to saidpopulation of human PDX1-positive pancreatic endoderm cells at aconcentration of about 40 ng/ml.

281. The method of paragraph 274, wherein the step of obtaining apopulation of human PDX1-positive pancreatic endoderm cells comprisesthe steps of obtaining a population of human foregut endoderm cells,said human foregut endoderm cells being PDX1-negative multipotent cellsthat can differentiate into cells, tissues or organs derived from theanterior portion of the gut tube and providing said population of humanforegut endoderm cells with a retinoid, thereby producing a populationof human PDX1-positive pancreatic endoderm cells.

282. The method of paragraph 281, wherein said retinoid is retinoic acid(RA).

283. The method of paragraph 282, wherein RA is provided to saidpopulation of human foregut endoderm cells at a concentration rangingfrom about 1 nM to about 10 μM.

284. The method of paragraph 281, wherein the step of obtaining apopulation of human foregut endoderm cells comprises the steps ofobtaining a population of human definitive endoderm cells, said humandefinitive endoderm cells being multipotent cells that can differentiateinto cells of the gut tube or organs derived therefrom and providingsaid population of human definitive endoderm cells with fibroblastgrowth factor 10 (FGF-10) and a hedgehog pathway inhibitor, therebyproducing a population of human foregut endoderm cells.

285. The method of paragraph 284 further comprising withdrawing anexogenously added factor of the TGF-β superfamily that may be present insaid population of definitive endoderm cells.

286. The method of paragraph 285, wherein said growth factor of theTGF-β superfamily is selected from the group consisting of Nodal,activin A, activin B and combinations thereof.

287. The method of paragraph 286, wherein said growth factor of theTGF-β superfamily is activin A.

288. The method of paragraph 284, wherein said hedgehog inhibitorcomprises KAAD-cyclopamine.

289. The method of paragraph 288, wherein KAAD-cyclopamine is providedto said population of human definitive endoderm cells at a concentrationranging from about 0.01 μM to about 1 μM.

290. The method of paragraph 288, wherein KAAD-cyclopamine is providedto said population of human definitive endoderm cells at a concentrationof about 0.2 μM.

291. The method of paragraph 284, wherein FGF-10 is provided to saidpopulation of human definitive endoderm cells at a concentration rangingfrom about 1 ng/ml to about 1000 ng/ml.

292. The method of paragraph 284, wherein FGF-10 is provided to saidpopulation of human definitive endoderm cells at a concentration rangingfrom about 10 ng/ml to about 100 ng/ml.

293. The method of paragraph 284, wherein FGF-10 is provided to saidpopulation of human definitive endoderm cells at a concentration ofabout 50 ng/ml.

294. The method of paragraph 284, wherein the step of obtaining apopulation of human definitive endoderm cells comprises the steps ofobtaining a population of human pluripotent cells and providing saidpopulation of human pluripotent cells with at least one growth factor ofthe TGF-β superfamily.

295. The method of paragraph 294, wherein said at least one growthfactor is Nodal.

296. The method of paragraph 294, wherein said at least one growthfactor is activin A.

297. The method of paragraph 294, wherein said at least one growthfactor is activin B.

298. The method of paragraph 294 further comprising providing saidpopulation of human pluripotent cells with wingless-type MMTVintegration site family member 3A (Wnt3A).

299. The method of paragraph 294, wherein a plurality of growth factorsof the TGFβ superfamily is provided.

300. The method of paragraph 299, wherein Wnt3A is also provided.

301. The method of paragraph 294, wherein said at least one growthfactor is provided in a concentration of at least about 10 ng/ml.

302. The method of paragraph 294, wherein said at least one growthfactor is provided in a concentration of at least about 100 ng/ml.

303. The method of paragraph 294, wherein said at least one growthfactor is provided in a concentration of at least about 500 ng/ml.

304. The method of paragraph 294, wherein said at least one growthfactor is provided in a concentration of at least about 1000 ng/ml.

305. The method of paragraph 294, wherein said at least one growthfactor is provided in a concentration of at least about 5000 ng/ml.

306. The method of paragraph 294, wherein said human pluripotent cellsare differentiated to human definitive endoderm cells in a mediumcomprising less than about 2% serum.

307. The method of paragraph 294, wherein said human pluripotent cellsare human embryonic stem cells derived from a tissue selected from thegroup consisting of the morula, the ICM of an embryo and the gonadalridges of an embryo.

308. An enriched, in vitro human pancreatic islet hormone-expressingcell population derived in vitro from human pluripotent cells.

309. The enriched, in vitro human pancreatic islet hormone-expressingcell population of paragraph 308, wherein said enriched cell populationis produced by the method of paragraph 253.

310. The enriched, in vitro human pancreatic islet hormone-expressingcell population of paragraph 308, wherein said enriched cell populationis produced by the method of paragraph 294.

311. The enriched, in vitro human pancreatic islet hormone-expressingcell population of paragraph 309 or 310, wherein at least about 25% ofsaid enriched human cell population comprises human pancreatic islethormone-expressing cells that express at least one marker selected fromthe group consisting of ghrelin, islet amyloid polypeptide (IAPP),insulin (INS), glucagon (GCG), NKX6 transcription factor related, locus1 (NKX6.1), somatostatin (SOM), and pancreatic polypeptide (PP) and donot substantially express at least one marker selected from the groupconsisting of AFP, SOX7, SOX1, ZIC1 and NFM.

312. The enriched, in vitro human pancreatic islet hormone-expressingcell population of paragraph 311, wherein at least about 50% of saidenriched human cell population comprises human pancreatic islethormone-expressing cells that express at least one marker selected fromthe group consisting of ghrelin, islet amyloid polypeptide (IAPP),insulin (INS), glucagon (GCG), NKX6 transcription factor related, locus1 (NKX6.1), somatostatin (SOM), and pancreatic polypeptide (PP) and donot substantially express at least one marker selected from the groupconsisting of AFP, SOX7, SOX1, ZIC1 and NFM.

313. The enriched, in vitro human pancreatic islet hormone-expressingcell population of paragraph 311, wherein at least about 90% of saidenriched human cell population comprises human pancreatic islethormone-expressing cells that express at least one marker selected fromthe group consisting of ghrelin, islet amyloid polypeptide (IAPP),insulin (INS), glucagon (GCG), NKX6 transcription factor related, locus1 (NKX6.1), somatostatin (SOM) and pancreatic polypeptide (PP) and donot substantially express at least one marker selected from the groupconsisting of AFP, SOX7, SOX1, ZIC1 and NFM.

314. An ex vivo reagent-cell complex comprising a human endocrineprecursor cell expressing NCAM, said endocrine precursor cell being amultipotent cell that can differentiate into human pancreatic islethormone-expressing cells, and a reagent bound to said NCAM.

315. The ex vivo reagent-cell complex of paragraph 314, wherein saidreagent comprises a molecule selected from the group consisting of ananti-NCAM antibody, an anti-NCAM antibody fragment and an NCAM ligand.

316. The ex vivo reagent-cell complex of paragraph 315, wherein saidNCAM ligand is NCAM Binding Protein 10 (NBP10).

317. The ex-vivo reagent-cell complex of paragraph 315, wherein saidreagent is an anti-NCAM antibody.

318. The ex vivo reagent-cell complex of paragraph 317, wherein saidanti-NCAM antibody is labeled.

319. The ex vivo reagent-cell complex of paragraph 318, wherein saidanti-NCAM antibody is fluorescently labeled.

320. The ex vivo reagent-cell complex of paragraph 314 furthercomprising a secondary reagent that binds to said reagent.

321. The ex vivo reagent-cell complex of paragraph 320, wherein saidreagent comprises and anti-NCAM antibody and wherein said secondaryreagent that binds to said anti-NCAM antibody is fluorescently labeled.

322. An ex vivo reagent-cell complex comprising a human immature islethormone-expressing cell expressing NCAM, said human immature islethormone-expressing cell being a multipotent cell that can differentiateinto human pancreatic islet hormone-expressing cell, and a reagent boundto said NCAM.

323. The ex vivo reagent-cell complex of paragraph 322, wherein saidreagent comprises a molecule selected from the group consisting of ananti-NCAM antibody, an anti-NCAM antibody fragment and an NCAM ligand.

324. The ex vivo reagent-cell complex of paragraph 323, wherein saidNCAM ligand is NCAM Binding Protein 10 (NBP10).

325. The ex-vivo reagent-cell complex of paragraph 323, wherein saidreagent is an anti-NCAM antibody.

326. The ex vivo reagent-cell complex of paragraph 325, wherein saidanti-NCAM antibody is labeled.

327. The ex vivo reagent-cell complex of paragraph 326, wherein saidanti-NCAM antibody is fluorescently labeled.

328. The ex vivo reagent-cell complex of paragraph 322 furthercomprising a secondary reagent that binds to said reagent.

329. The ex vivo reagent-cell complex of paragraph 328, wherein saidreagent comprises and anti-NCAM antibody and wherein said secondaryreagent that binds to said anti-NCAM antibody is fluorescently labeled.

330. The method of any one of paragraphs 86, 150, 222 or 294, whereinsaid human pluripotent cells are human embryonic stem cells derived froma preimplantation embryo.

331. A method of producing human pancreatic hormone-expressing cells,said method comprising the steps of: (a) providing a population ofpluripotent human embryonic stem cells (hESCs) with at least one growthfactor of the TGF-β superfamily, thereby producing a population of humandefinitive endoderm cells; (b) providing said population of humandefinitive endoderm cells with at least one fibroblast growth factor,thereby producing a population of human foregut endoderm cells; (c)providing said population of human foregut endoderm cells with noggin,thereby producing a population comprising human endocrine precursorcells; and (d) incubating said population of human endocrine precursorcells in a culture medium for a sufficient time to permit humanpancreatic islet hormone-expressing cells to form, wherein saidsufficient time for human pancreatic hormone-expressing cells to formhas been determined by detecting the presence of human pancreatichormone-expressing cells in said cell population.

332. The method of paragraph 331, wherein at least about 2% of saidhuman cells in said cell population differentiate into human pancreatichormone-expressing cells.

333. The method of paragraph 331, wherein at least about 5% of saidhuman cells in said cell population differentiate into human pancreatichormone-expressing cells.

334. The method of paragraph 331, wherein at least about 10% of saidhuman cells in said cell population differentiate into human pancreatichormone-expressing cells.

335. The method of paragraph 331, wherein at least about 20% of saidhuman cells in said cell population differentiate into human pancreatichormone-expressing cells.

336. The method of paragraph 331, wherein at least about 40% of saidhuman cells in said cell population differentiate into human pancreatichormone-expressing cells.

337. The method of paragraph 331, wherein at least about 50% of saidhuman cells in said cell population differentiate into human pancreatichormone-expressing cells.

338. The method of paragraph 331, wherein at least about 70% of saidhuman cells in said cell population differentiate into human pancreatichormone-expressing cells.

339. The method of paragraph 331, wherein at least about 90% of saidhuman cells in said cell population differentiate into human pancreatichormone-expressing cells.

340. The method of paragraph 331, wherein detecting the presence ofhuman pancreatic islet hormone-expressing cells in said cell populationcomprises detecting the expression of at least one marker selected fromthe group consisting of pancreatic duodenal homeobox 1 (PDX1), ghrelin(GHRL), insulin (INS), islet amyloid polypeptide (IAPP), pancreaticpolypeptide (PP), ISL1 transcription factor (ISL1), NKX6 transcriptionfactor related locus 1 (NKX6.1) and paired box 6 (PAX6) in cells of saidcell population.

341. The method of paragraph 340, wherein the expression of at least oneof said markers is determined by Q-PCR.

342. The method of paragraph 340, wherein the expression of at least oneof said markers is determined by immunocytochemistry.

343. The method of paragraph 331 further comprising providing the cellpopulation with a gamma secretase inhibitor.

344. The method of paragraph 343, wherein said gamma secretase inhibitorcomprises N—[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycinet-butyl ester (DAPT).

345. The method of paragraph 343, wherein said gamma secretase inhibitoris provided to the cell population at about the same time as providingnoggin or after providing noggin.

346. The method of paragraph 344, wherein said gamma secretase inhibitoris provided to the cell population at a concentration ranging from about0.1 μM to about 10 μM.

347. The method of paragraph 331, wherein said at least one fibroblastgrowth factor is fibroblast growth factor 7 (FGF-7).

348. The method of paragraph 347, wherein said FGF-7 is provided to thecell culture at a concentration ranging from about 1 ng/ml to about 1000ng/ml.

349. The method of paragraph 331 further comprising providing the cellpopulation with a hedgehog inhibitor at about the same time as addingthe at least one fibroblast growth factor.

350. The method of paragraph 349, wherein said hedgehog inhibitorcomprises KAAD-cyclopamine.

351. The method of paragraph 350, wherein said KAAD-cyclopamine isprovided to the cell population at a concentration ranging from about0.01 μM to about 10 μM.

352. The method of paragraph 331 further comprising withdrawing anygrowth factor of the TGF-β superfamily that may be present in saidpopulation of definitive endoderm cells.

353. The method of paragraph 331, wherein said growth factor of theTGF-β superfamily is selected from the group consisting of Nodal,activin A, activin B and combinations thereof.

354. The method of paragraph 353, wherein said growth factor of theTGF-β superfamily comprises activin A.

355. The method of paragraph 354, wherein said activin A is provided tosaid hESCs at a concentration ranging from about 10 ng/ml to about 1000ng/ml.

356. The method of paragraph 331 further comprising providing the hESCswith wingless-type MMTV integration site family member 3A (Wnt3A).

357. The method of paragraph 356, wherein said Wnt3A is provided at aconcentration ranging from about 1 ng/ml to about 1000 ng/ml.

358. The method of paragraph 331, wherein said hESCs are differentiatedto human definitive endoderm cells in a medium comprising less thanabout 2% serum.

359. The method of paragraph 331, wherein said hESCs are derived from atissue selected from the group consisting of the morula, the ICM of anembryo and the gonadal ridges of an embryo.

360. The method of paragraph 331 further comprising providing a retinoidto the cell population at about the same time as providing noggin.

361. The method of paragraph 331 further comprising providing a retinoidto the cell population at about the same time or after adding at leastone fibroblast growth factor.

362. The method of paragraph 360 or 361, wherein the retinoid isretinol.

363. The method of paragraph 360 or 361, wherein the retinoid isretinoic acid.

364. The method of paragraph 363, wherein the retinoic acid is providedat a concentration ranging from about 0.01 μM to about 10 μM.

365. The cell culture or cell population of any one of paragraphs 1-49,164-173, 236-252 or 308-313, wherein at least some of the cells arenon-recombinant cells.

366. The cell culture or cell population of any one of paragraphs 1-49,164-173, 236-252 or 308-313, wherein the cells are non-recombinantcells.

367. The cell culture or cell population of any one of paragraphs 1-49,164-173, 236-252 or 308-313, wherein the cells have not been cultured inthe presence of a histone deacetylase inhibitor.

368. The cell culture or cell population of paragraph 367, wherein saidhistone deacetylase inhibitor comprises sodium butyrate.

369. The method of any one of paragraphs 50-163, 174-235, 253-307 or331-364, wherein at least some of the cells are non-recombinant cells.

370. The method of any one of paragraphs 50-163, 174-235, 253-307 or331-364, wherein the cells are non-recombinant cells.

371. The method of any one of paragraphs 50-163, 174-235, 253-307 or331-364, wherein the cells have not been cultured in the presence of ahistone deacetylase inhibitor.

372. The method of paragraph 371, wherein said histone deacetylaseinhibitor comprises sodium butyrate.

It will be appreciated that the methods and compositions described aboverelate to cells cultured in vitro. However, the above-described in vitrodifferentiated cell compositions may be used for in vivo applications,such as cell replacement therapies.

Additional embodiments of the present invention may also be found inU.S. Provisional Patent Application No. 60/532,004, entitled DEFINITIVEENDODERM, filed Dec. 23, 2003; U.S. Provisional Patent Application No.60/566,293, entitled PDX1 EXPRESSING ENDODERM, filed Apr. 27, 2004; U.S.Provisional Patent Application No. 60/586,566, entitled CHEMOKINE CELLSURFACE RECEPTOR FOR THE ISOLATION OF DEFINITIVE ENDODERM, filed Jul. 9,2004; U.S. Provisional Patent Application No. 60/587,942, entitledCHEMOKINE CELL SURFACE RECEPTOR FOR THE ISOLATION OF DEFINITIVEENDODERM, filed Jul. 14, 2004; U.S. patent application Ser. No.11/021,618, entitled DEFINITIVE ENDODERM, filed Dec. 23, 2004 and U.S.patent application Ser. No. 11/115,868, entitled PDX1 EXPRESSINGENDODERM, filed Apr. 26, 2005; U.S. patent application Ser. No.11/165,305, entitled METHODS FOR IDENTIFYING FACTORS FOR DIFFERENTIATINGDEFINITIVE ENDODERM, filed Jun. 23, 2005; U.S. Provisional PatentApplication No. 60/730,917, entitled PDX1-EXPRESSING DORSAL AND VENTRALFOREGUT ENDODERM, filed Oct. 27, 2005; U.S. Provisional PatentApplication No. 60/736,598, entitled MARKERS OF DEFINITIVE ENDODERM,filed Nov. 14, 2005; U.S. Provisional Patent Application No. 60/778,649,entitled INSULIN-PRODUCING CELLS AND METHOD OF PRODUCTION, filed Mar. 2,2006; U.S. Provisional Patent Application No. 60/833,633, entitledINSULIN-PRODUCING CELLS AND METHOD OF PRODUCTION, filed Jul. 26, 2006;and U.S. Provisional Patent Application No. 60/852,878, entitledENRICHMENT OF ENDOCRINE PRECURSOR CELLS, IMMATURE PANCREATIC ISLET CELLSAND MATURE PANCREATIC ISLET CELLS USING NCAM, filed Oct. 18, 2006, thedisclosures of which are incorporated herein by reference in theirentireties.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic showing the steps in the in vitro differentiationof hESCs to islet cells through the intermediate stages that correspondto those observed during development of the pancreas in vivo. Sequentialtreatments with various growth factors/media combinations, which areused to elicit this step-wise differentiation of hESCs through eachintermediate, are shown. Conditions and cell characteristics aredepicted in the boxes. Below the boxes is an exemplary time line showinga typical differentiation from human embryonic stem cells (hESCs) topancreatic islet hormone-expressing cells with time units indicated inhours (h) or days (d). Below each intermediate is a list of genes forwhich expression is characteristic of, although not necessarilyexclusive for, that intermediate. Monitoring the expression of one ormultiple genes for each intermediate along this progression allows forrobust demonstration of the occurrence of each transition in vitro.Abbreviations are as follows: ESC—embryonic stem cell; ME—mesendoderm;Ant. DE—anterior definitive endoderm.

FIGS. 2A-N are bar charts showing the relative expression of variousmarkers during a 21 day differentiation protocol. Markers that displaysubstantial differences in differentiation generated as a result of thethree conditions used in step 1 of differentiation are (A) SOX17, (B)CXCR4, (C) SOX7, (D) ISL1, (E) SOX1 and (F) PAX6. Panels (G) PDX1, (H)NGN3, (I) NKX2.2 and (J) NKX6.1 show the relative expression of markersassociated with the differentiation of hESCs to pancreatic endoderm andendocrine precursor cells. Panels (K) insulin, (L) glucagon, (M) ghrelinand (N) SOM show the relative expression of the islet hormones insulin,glucagon, ghrelin, and somatostatin near the end of the differentiationprocess.

FIGS. 3A-L are bar charts showing the relative expression of (A) FOXA1,(B) HNF1b, (C) HNF6, (D) PDX1, (E) NGN3, (F) PAX4, (G) NKX2.2, (H)NKX6.1, (I) ghrelin, (J) glucagon, (K) insulin and (L) IAPP from day 0to day 16 of a differentiation protocol.

FIG. 4A depicts a Western blot analysis of PDX1 protein expression incells subjected to different media conditions. Abbreviations:MS1-PDX1—Protein lysate from MS1 cells transfected with PDX1 (positivecontrol), A100—100 ng/ml activin A; A25R2—25 ng/ml activin A and 2 μMRA; RP—RPMI medium; CM—CMRL medium; Ex—40 ng/ml exendin 4.

FIG. 4B is a bar chart showing the relative expression of PDX1 mRNA inthe 7 day, 8 day and 9 day cultures set forth in FIG. 4(A).

FIGS. 5A-H are bar charts showing the relative expression of (A) HB9,(B) PDX1, (C) NGN3, and (D) NKX2.2 after 13 days of differentiation and(E) PDX1, (F) NKX2.2, (G) insulin and (H) glucagon after 17 days ofdifferentiation in the presence or absence of retinoic acid.

FIGS. 6A-F are bar charts showing the relative expression of (A) NGN3,(B) NKX2.2, (C) insulin, (D) glucagon, (E) ghrelin, and (F) somatostatin(SOM) after 19 days of differentiation and exposure to three differentconcentrations of the gamma secretase inhibitor DAPT or no DAPT at all.

FIGS. 7A-D are photomicrographs of (A) insulin, (B) glucagon and (C)somatostatin (SOM) immunoreactive cells. The merge of these three imagesis shown (D) and triple labeled cells are identified by the arrowheads.

FIGS. 8A-D are photomicrographs showing immunoreactivity for (A) insulinand (B) PAX6. These micrographs indicate that insulin positive cells arealso PAX6 positive. Photomicrographs showing immunoreactivity for (C)insulin and (D) ISL1 indicate that insulin positive cells are also ISL1positive. There are also many ISL1 cells that are negative for insulinimmunoreactivity (compare C and D).

FIGS. 9A-B are bar charts showing that insulin mRNA detection, panel A,correlates with the ability to measure C-peptide released into theculture media, panel B. Abbreviations are as follows: A100—100 ng/mlactivin A; 2NF—2% fetal bovine serum (FBS) and no factors; Fstnog—50ng/ml follistatin and 100 ng/ml noggin; “B”—cultures receiving A100 ondays 1-5, “C”—cultures receiving 2% FBS and no factors on days 1-5; and“D”—cultures receiving 50 ng/ml follistatin and 100 ng/ml noggin on days1-5.

FIGS. 10A-B are bar charts showing that conditions which display robustinsulin mRNA detection, panel A also display glucose stimulatedC-peptide secretion, panel B. Abbreviations are as follows: g50—1.6 mMglucose; g400—16 mM glucose.

FIGS. 11A-F are bar charts showing that hESC lines BG01 and BG02 arecapable of differentiation to pancreatic islet hormone-expressing cells.Panels A and B show the upregulation of PDX1 mRNA for BG01 (A) and BG02(B); panels C and D show upregulation of NGN3 mRNA for BG01 (C) and BG02(D); and panels E and F show the upregulation of insulin expression forBG01 (E) and BG02(F).

FIGS. 12A-D are photomicrographs showing immunoreactivity ofhESC-derived cells treated to differentiate to early pancreatic islethormone-expressing cells for NCAM (12C) and NKX2.2 (12B). Total cellpopulation is stained with DAPI (12A). These micrographs indicate thatNKX2.2-positive cells are also NCAM positive (12D).

FIGS. 13A-D are photomicrographs showing immunoreactivity ofhESC-derived cells treated to differentiate to immature pancreatic islethormone-expressing cells for NCAM (13C) and insulin (13B). Total cellpopulation is stained with DAPI (13A). These micrographs indicate thatinsulin-positive cells are also NCAM positive (13D).

FIGS. 14A-F are photomicrographs showing immunoreactivity ofhESC-derived cells treated to differentiate to immature pancreatic islethormone-expressing cells for NCAM (14E), INS (14F) and PAX6 (14D). Totalcell population is stained with DAPI (14A). These micrographs indicatethat PAX6-positive cells are also NCAM positive (14B) and thatINS-positive cells are also NCAM positive (14C).

FIGS. 15A and 15B is a photomicrograph showing immunoreactivity ofhESC-derived cells treated to differentiate to immature pancreatic islethormone-expressing cells for NKX2.2 and synaptophysin. These micrographsindicate that synaptophysin-positive cells are also NKX2.2 positive (15Aand 15B).

FIGS. 16A-D are photomicrographs showing immunoreactivity ofhESC-derived cells treated to differentiate to endocrine precursor cellsfor MAFB and INS. FIGS. 16A and 16B show that MAFB and INS areco-expressed in hESC-derived endocrine precursor cells. FIGS. 16C and16D show the immunoreactivity of 13.5 week old human fetal pancreas forMAFB and INS. MAFB and INS are co-expressed in fetal pancreas.

FIGS. 17A-B are flow cytometry dot plots showing the co-segregation ofimmature pancreatic islet hormone-expressing cells expressingsynaptophysin and NCAM (17A) as well as the co-segregation of immaturepancreatic islet hormone-expressing cells expressing INS and NCAM (17B).

FIGS. 18A-D are flow cytometry dot plots of hESC-derived cells treatedto differentiate to immature pancreatic islet hormone-expressing cells.FIG. 18A is a flow cytometry dot plot showing labeling of hESC-derivedcells that have been treated to differentiate into immature pancreaticislet hormone-expressing cells with anti-NCAM antibody. FIG. 18B is aflow cytometry dot plot showing the distribution of hESC-derived cellsthat are positive or negative for both NCAM and SYP. FIG. 18C is a flowcytometry dot plot showing the distribution of hESC-derived NCAMpositive cells of FIG. 18A that have been re-analyzed by FACS for NCAMand SYP. The dot plot shows the distribution of these cells that arepositive or negative for both NCAM and SYP. FIG. 18D is a flow cytometrydot plot showing the distribution of hESC-derived NCAM negative cells ofFIG. 18A that have been re-analyzed by FACS for NCAM and SYP. The dotplot shows the distribution of these cells that are positive or negativefor both NCAM and SYP.

FIGS. 19A-D are flow cytometry dot plots of hESC-derived cells that havebeen treated to differentiate to immature pancreatic islethormone-expressing cells. The treated cells that have (19B, 19D) or havenot (19A, 19C) been sorted for NCAM positive cells. FIGS. 19A and 19Bshow the distribution of cells that are positive and negative for bothNCAM and SYP. FIGS. 19C and 19D show the distribution of cells that arepositive and negative for both NCAM and INS.

FIGS. 20A-C are flow cytometry dot plots of hESC-derived cells that havebeen treated to differentiate to immature pancreatic islethormone-expressing cells. FIG. 20A shows a small population of the cellsstain brightly for NCAM. FIG. 20B shows a small population of the cellsstain brightly for SYP. FIG. 20C shows that a much higher percentage ofthe hESC-derived cells are SYP positive if the NCAM bright cells of FIG.20A are collected and analyzed for SYP.

FIGS. 21A-C are flow cytometry dot plots of hESC-derived cells that havebeen treated to differentiate to immature pancreatic islethormone-expressing cells. FIG. 21A shows the distribution ofhESC-derived cells stained for NCAM. FIG. 21B shows a small populationof hESC cells treated to differentiate to immature pancreatic islethormone-expressing cells are both NCAM positive and CD133 negative. FIG.21C shows the distribution of NCAM positive/CD133 negative cells thatare SYP positive and SYP negative.

FIGS. 22A-K are bar charts showing the mRNA levels of certain markers asdetected by QPCR in hESC-derived cells that have been treated todifferentiate to endocrine precursor cells (“early”) or that have beentreated to differentiate to immature pancreatic islet hormone-expressingcells (“middle” and “late”). The data labeled “Presort” represent markermRNA levels in cells that have not been processed and sorted through aFACS machine. The data labeled “NCAM bright” represent marker mRNAlevels in cells that are NCAM positive. The data labeled “NCAM dim”represent marker mRNA levels in cells that are NCAM negative.Specifically shown are the mRNA levels of NGN3 (22A), PAX4 (22B), INS(22C), Pancreatic polypeptide (22D), PAX6 (22E), GCG (22F), GHRL (22G),GCK (22H), SST (22I), NXK2.2 (22J) and SYP (22K).

FIGS. 23A-E are bar charts showing the mRNA levels of certain markers asdetected by QPCR in hESC derived cells that have been treated todifferentiate to immature pancreatic islet hormone-expressing cells (day19). The data labeled “Presort” represent marker mRNA levels in cellsthat have not been processed and sorted through a FACS machine. The datalabeled “NCAM bright” represent marker mRNA levels in cells that areNCAM positive. The data labeled “NCAM dim” represent marker mRNA levelsin cells that are NCAM negative. Specifically shown are the mRNA levelsof NEUROD (23A), ISL1 (23B), GAS (23C), KIR6.2 (23D), and SUR1 (23E).

FIGS. 24A-K are bar charts showing the mRNA levels of certain markers asdetected by QPCR in hESC derived cells that have been treated todifferentiate to immature pancreatic islet hormone-expressing cells (day19). The data labeled “Presort” represent marker mRNA levels in cellsthat have not been passed through but not sorted in a FACS machine(live, gated cells). The data labeled “NCAM bright” represent markermRNA levels in cells that are NCAM positive. Specifically shown are themRNA levels of NCAM1 (24A), NKX2.2 (24B), SYP (24C), PAX6 (24D), NEUROD(24E), ISL1 (24F), INS (24G), GCG (24H), GHRL (24I), SST (24J) and PP(24K).

FIGS. 25A-F are flow cytometry dot plots of hESC-derived cells that havebeen treated to differentiate to immature pancreatic islethormone-expressing cells. FIGS. 25A, 25C and 25E show the proportion ofNCAM positive cells that are SYP, CHGA, and INS positive, respectively,in the cell population prior to sorting the population for NCAM positivecells. FIGS. 25B, 25D, and 25F show the percentage of cells that areSYP, CHGA and INS positive, respectively, following sorting the cellsfor those that are positive for NCAM expression.

FIGS. 26A-C are flow cytometry dot plots of hESC-derived cells that havebeen treated to differentiate to immature pancreatic islethormone-expressing cells. FIG. 26A shows the proportion of NCAM positivecells that are SYP positive. FIG. 26B shows the proportion of NCAMpositive cells that are CD133 negative. FIG. 26C shows the proportion ofcells that have been sorted for NCAM positive/CD133 negative cells,which are SYP positive.

FIGS. 27A-D are photomicrographs showing immunoreactivity of immaturepancreatic islet hormone-expressing cells for INS (27D), PAX6 (27C).Total cell population is stained with DAPI (27B). The cells arehESC-derived stem cells treated to differentiate to immature pancreaticislet hormone-expressing cells and sorted using Fluorescence ActivatedCell Sorting technology. The cells represented in the micrographs alsostained brightly for NCAM. A proportion of the NCAM positivehESC-derived cells co-express PAX6 and INS (27A).

FIGS. 28A-D are photomicrographs showing immunoreactivity of immaturepancreatic islet hormone-expressing cells expressing INS (28C) or GCG(28D). The cells are hESC-derived stem cells treated to differentiate toimmature pancreatic islet hormone-expressing cells and sorted usingFluorescence Activated Cell Sorting technology. The cells represented inthe micrographs also stained brightly for NCAM. FIG. 28A shows theoverlap of cells that express both INS and GCG.

FIGS. 29A-F are bar charts showing the mRNA levels of certain markers asdetected by QPCR in hESC derived cells that have been treated todifferentiate to pancreatic insulin-expressing cells (day 19).Specifically shown are the mRNA levels of PDX1 (29A), NGN3 (29B), INS(29C), SST (29D), GCG (29E) and GHRL (29F). The abbreviations areindicated as follows: A100—100 ng/ml activin A; KC—50 ng/ml KGF and 0.25μM KAAD cyclopamine; and nog—noggin.

FIGS. 30A-F are bar charts showing the mRNA levels of certain markers asdetected by QPCR in hESC derived cells that have been treated todifferentiate to hormone-expressing cells (day 11). Specifically shownare the mRNA levels of PDX1 (30A), NGN3 (30B), PTF1A (30C), NKX6.1(30D), INS (30E) and GCG (30F). The abbreviations are indicated asfollows: A100—100 ng/ml activin A; KC—50 ng/ml KGF and 0.25 μM KAADcyclopamine; N—noggin; CR0.1—0.25 μM KAAD cyclopamine and 0.1 μMretinoic acid; CR 2—0.25 μM KAAD cyclopamine and 2 μM retinoic acid;“A”—0 ng/ml noggin and 0.1 μM retinoic acid; “B”—30 ng/ml noggin and 0.1μM retinoic acid; “C”—100 ng/ml noggin and 0.1 μM retinoic acid; “D”—0ng/ml noggin and 2 μM retinoic acid; “E”—30 ng/ml noggin and 2 μMretinoic acid and “F” 100 ng/ml noggin and 2 μM retinoic acid.

DETAILED DESCRIPTION

Described herein is a progression of steps for convertingundifferentiated hESCs to endocrine precursor cells and immaturepancreatic islet hormone-expressing cells, and ultimately to maturepancreatic endocrine cells (mature pancreatic islet hormone-expressingcells) capable of synthesizing insulin, glucagon, somatostatin,pancreatic polypeptide, PPY and ghrelin in vitro. This progression ofsteps directs the sequential differentiation of hESCs throughintermediates that are currently recognized to occur during pancreaticdevelopment in vivo. The general method for production of hESC-derivedpancreatic endocrine cells begins with the production of definitiveendoderm (DE), followed by a DE patterning step in which TGF-betasignaling is modified and a fibroblast growth factor or a ligand thatstimulates or otherwise interacts with the fibroblast growth factor 2receptor IIIb (FGFR2(IIIb) is supplied. The PDX1-positive pre-patternedendoderm is further recruited into the pancreatic endocrine lineage bytransient exposure to retinoic acid and gamma secretase inhibition afterwhich pancreatic endocrine hormone producing cells are generated.

As previously demonstrated in U.S. patent application Ser. No.11/021,618, entitled DEFINITIVE ENDODERM, filed Dec. 23, 2004 andD'Amour et al. Nat. Biotech. 23, 1534-1541, (2005), the disclosures ofwhich are incorporated herein by reference in their entireties, we havedeveloped robust methods for the production of the somatic germ layerdefinitive endoderm (DE). In vivo, the DE lineage is generated duringthe gastrulation stage of embryonic development arising in an areatermed the primitive streak. Generation of DE is a prerequisite forlatter specification of tissues and organs such as intestine, stomach,lungs, thymus, pancreatic endocrine, parathyroid, thyroid and pancreas.

In humans as well as most other vertebrates, the pancreas is derivedfrom the foregut endoderm at the foregut-midgut junction as both aventral and dorsal pancreatic bud. In humans, the dorsal and ventralbuds fuse at approximately 41-45 days post conception (p.c.) with thesmaller ventral bud forming the posterior portion of the head of thepancreas and a region termed the uncinate process (Bocian-Sobkowska, J.,et al. Histochem. Cell Biol. 112, 147-153, (1999)). This region inhumans is composed primarily of pancreatic polypeptide producing isletcells (Rahier J., et al., Cell Tissue Res. 200 (3), 359-366, (1979);Malaisse-Langae F., et al., Diabetologia 17(6), 361-365, (1979); FioccaR., et al., Histochemistry 77(4), 511-523, (1983); Stefan Y., et al.,Diabetologica 23(2), 141-142, (1982)). The dorsal pancreatic bud formsthe anterior portion of the head, the body and the tail of the pancreasin humans. It makes all pancreatic hormone producing cells. In frog(Xenopus) and fish (zebrafish) only the dorsal bud cells go on to makeinsulin producing islet cells (Kelly, O. G. and Melton, D. A., Dev. Dyn.218, 615-627, (2000); Chen, Y., et al., Dev. Biol. 271(1), 144-160,(2004); Field, H. A., et al., Dev. Biol. 263, 197-208 (2003)).Similarly, the ventral bud in human appears to make predominantlypancreatic polypeptide expressing islet cells to the exclusion ofinsulin (Rahier J., et al., Cell Tissue Res. 200 (3), 359-366, (1979);Malaisse-Langae F., et al., Diabetologia 17(6), 361-365, (1979); FioccaR., et al., Histochemistry 77(4), 511-523, (1983); Stefan Y., et al.,Diabetologica 23(2), 141-142, (1982)). In contrast, in the rat and mouseboth ventral and dorsal buds make insulin producing islets (Spooner, B.S., et al., J. Cell Biology, 47, 235-246, (1970); Li, H., et al., Nature23, 67-70, (1999)).

As depicted in FIG. 1, pancreatic endocrine cells can be efficientlyproduced from hESCs in a series of developmental steps. The first stepis the formation of mesendoderm (ME) characterized by the transitionalexpression of the T-box gene brachyury. As hESCs differentiate to DEthey down regulate E-cadherin and transition from an epithelial epiblaststate to a mesenchymal DE cell (D'Amour et al. Nat. Biotech. 23,1534-1541, (2005)). The principal markers defining the early DE cell areFOXA2, GSC, N-cadherin, CXCR4 and SOX17. As explained in our previousU.S. patent application Ser. No. 11/021,618, DE is further characterizedby the absence of significant expression of certain other markers, suchas SOX1, SOX7, thrombomodulin (TM), SPARC and alpha fetoprotein (AFP).The nascent DE is further patterned from its strong anterior characterto a more posterior but still foregut endoderm by removal of activinsignaling. Such foregut endoderm is characterized by expression of theHNF1b, and FOXA1 gene markers. This endoderm expands and assumes a moredorsal phenotype by exposure to FGF10, retinoic acid and cyclopamine(Sonic Hedgehog (SHH) inhibitor). The posterior foregut (posteriorregion of the foregut) patterned cells express PDX1, PTF1a, HNF1b,Onecut1/2 and HB9. These pancreatic endoderm cells are recruitedpreferentially to the endocrine lineage by modulation of gamma secretasesignaling (potentially due to the inhibition of Notch pathway signaling)as indicated by the transient expression of NGN3, indicative ofendocrine precursor cells. The hESC-derived endocrine precursor cellsalso express paired box gene 4 (PAX4), and NKX2.2. Further incubation ofendocrine precursor cells gives rise to immature pancreatic islethormone-expressing cells. Immature pancreatic islet hormone-expressingcells express V-maf musculoaponeurotic fibrosarcoma oncogene homolog B(MAFB), as well as NKX2.2 and pancreatic islet hormone-expressing cellsexpress NKX2.2. Finally, further incubation of immature pancreatic islethormone-expressing cells results in the transition from the immaturecells to mature pancreatic islet hormone-expressing cells that canexpress V-maf musculoaponeurotic fibrosarcoma oncogene homolog A (MAFA)in addition to the endocrine hormones insulin, glucagon, somatostatin,-PPY, ghrelin and the pancreatic transcription factors NKX2.2/6.1, PAX6,NEUROD1, PDX1, ISL1.

DEFINITIONS

It will be appreciated that the numerical ranges expressed hereininclude the endpoints set forth and describe all integers between theendpoints of the stated numerical range.

As used herein, “pancreatic islet hormone-expressing cell” refers to acell, which has been derived from a human pluripotent cell in vitro,which expresses one or more pancreatic hormones and which has at leastsome of the functions of a human pancreatic islet cell. Pancreatic islethormone-expressing cells can be mature or immature. Immature pancreaticislet hormone-expressing cells can be distinguished from maturepancreatic islet hormone-expressing cells based on the differentialexpression of certain markers. As used herein, “pancreatichormone-expressing cell” is used interchangeably with “pancreatic islethormone-expressing cell.”

As used herein, “endocrine precursor cell” refers to a multipotent cellof the definitive endoderm lineage that expresses neurogenin 3 (NEUROG3)and which can further differentiate into cells of the endocrine systemincluding, but not limited to, pancreatic islet hormone-expressingcells. Endocrine precursor cells cannot differentiate into as manydifferent cell, tissue and/or organ types as compared to lessspecifically differentiated definitive endoderm lineage cells, such asPDX1-positive pancreatic endoderm cell.

As used herein, “PDX1-positive pancreatic endoderm cell” and“PDX1-positive foregut endoderm cell” refer to a multipotent cell of thedefinitive endoderm lineage that expresses pancreatic and duodenalhomeobox gene 1 (PDX1) and which can further differentiate into cellsderived from the foregut including, but not limited to, endocrineprecursor and pancreatic islet hormone-expressing cells. PDX1-positivepancreatic endoderm cells cannot differentiate into as many differentcells, tissue and/or organ types as compared to definitive endodermcells.

As used herein, “multipotent” or “multipotent cell” refers to a celltype that can give rise to a limited number of other particular celltypes. Multipotent cells are committed to one or more embryonic cellfates, and thus, in contrast to pluripotent cells, cannot give rise toeach of the three embryonic cell lineages as well as extraembryoniccells.

In some embodiments, “pluripotent cells” are used as the startingmaterial for pancreatic islet hormone-expressing cell differentiation.By “pluripotent” is meant that the cell can give rise to each of thethree embryonic cell lineages as well as extraembryonic cells.Pluripotent cells, however, may not be capable of producing an entireorganism.

In certain embodiments, the pluripotent cells used as starting materialare stem cells, including human embryonic stem cells. As used herein,“embryonic” refers to a range of developmental stages of an organismbeginning with a single zygote and ending with a multicellular structurethat no longer comprises pluripotent or totipotent cells other thandeveloped gametic cells. In addition to embryos derived by gametefusion, the term “embryonic” refers to embryos derived by somatic cellnuclear transfer.

By “conditioned medium” is meant, a medium that is altered as comparedto a base medium. For example, the conditioning of a medium may causemolecules, such as nutrients and/or growth factors, to be added to ordepleted from the original levels found in the base medium. In someembodiments, a medium is conditioned by allowing cells of certain typesto be grown or maintained in the medium under certain conditions for acertain period of time. For example, a medium can be conditioned byallowing hESCs to be expanded, differentiated or maintained in a mediumof defined composition at a defined temperature for a defined number ofhours. As will be appreciated by those of skill in the art, numerouscombinations of cells, media types, durations and environmentalconditions can be used to produce nearly an infinite array ofconditioned media.

When used in connection with cell cultures and/or cell populations, theterm “portion” means any non-zero amount of the cell culture or cellpopulation, which ranges from a single cell to the entirety of the cellculture or cells population. In preferred embodiments, the term“portion” means at least 5%, at least 6%, at least 7%, at least 8%, atleast 9%, at least 10%, at least 11%, at least 12%, at least 13%, atleast 14%, at least 15%, at least 16%, at least 17%, at least 18%, atleast 19%, at least 20%, at least 21%, at least 22%, at least 23%, atleast 24%, at least 25%, at least 26%, at least 27%, at least 28%, atleast 29%, at least 30%, at least 31%, at least 32%, at least 33%, atleast 34%, at least 35%, at least 36%, at least 37%, at least 38%, atleast 39%, at least 40%, at least 41%, at least 42%, at least 43%, atleast 44%, at least 45%, at least 46%, at least 47%, at least 48%, atleast 49%, at least 50%, at least 51%, at least 52%, at least 53%, atleast 54%, at least 55%, at least 56%, at least 57%, at least 58%, atleast 59%, at least 60%, at least 61%, at least 62%, at least 63%, atleast 64%, at least 65%, at least 66%, at least 67%, at least 68%, atleast 69%, at least 70%, at least 71%, at least 72%, at least 73%, atleast 74%, at least 75%, at least 76%, at least 77%, at least 78%, atleast 79%, at least 80%, at least 81%, at least 82%, at least 83%, atleast 84%, at least 85%, at least 86%, at least 87%, at least 88%, atleast 89%, at least 90%, at least 91%, at least 92%, at least 93%, atleast 94% or at least 95% of the cell culture or cell population.

With respect to cells in cell cultures or in cell populations, the term“substantially free of” means that the specified cell type of which thecell culture or cell population is free, is present in an amount of lessthan about 10%, less than about 9%, less than about 8%, less than about7%, less than about 6%, less than about 5%, less than about 4%, lessthan about 3%, less than about 2% or less than about 1% of the totalnumber of cells present in the cell culture or cell population.

As used herein, “exogenously added,” compounds such as growth factors,differentiation factors, and the like, in the context of cultures orconditioned media, refers to growth factors that are added to thecultures or media to supplement any compounds or growth factors that mayalready be present in the culture or media. For example, in someembodiments, of the present invention, cells cultures and or cellpopulations do not include an exogenously-added retinoid.

As used herein, “produced from hESCs,” “derived from hESCs,”“differentiated from hESCs” and equivalent expressions refer to theproduction of a differentiated cell type from hESCs in vitro rather thanin vivo.

In some embodiments, hESCs can be derived from a “preimplantationembryo.” As used herein, “preimplantation embryo” refers to an embryobetween the stages of fertilization and implantation. Thus, apreimplantation embryo typically has not progressed beyond theblastocyst stage. Implantation usually takes place 7-8 days afterfertilization. However, implantation may take place about 2, about 3,about 4, about 5, about 6, about 7, about 8, about 9, about 10, about11, about 12, about 13, about 14 or greater than about 14 days afterfertilization.

As used herein, “hedgehog inhibitor” or “hedgehog pathway inhibitor”refers to any molecule that inhibits any member of the hedgehogsignaling pathway. Exemplary hedgehog pathway inhibitors include, butare not limited to, KAAD-cyclopamine, cyclopamine analogs, jervine,jervine analogs, hedgehog pathway blocking antibodies and any otherinhibitors of hedgehog pathway function known to those of ordinary skillin the art.

As used herein, “gamma secretase inhibitor” refers to any molecule thatinhibits gamma secretase or signaling events caused by the activity ofgamma secretase. Exemplary gamma secretase inhibitors include, but arenot limited to, N—[N-(3,5-Diflurophenacetyl-L-alanyl)]-S-phenylglycinet-Butyl Ester (DAPT), the F-box protein SEL-10, gamma secretase blockingantibodies and any other inhibitors of gamma secretase function known tothose of ordinary skill in the art. In some embodiments, the gammasecretase inhibitor inhibits the Notch signaling pathway. In someembodiments, a Notch pathway inhibitor or a Notch-specific inhibitor maybe used in place of a gamma secretase inhibitor.

As used herein, “retinoid” refers to retinol, retinal or retinoic acidas well as derivatives of any of these compounds. In a preferredembodiment, the retinoid is retinoic acid.

By “FGF family growth factor,” “a fibroblast growth factor” or “memberof the fibroblast growth factor family” is meant an FGF selected fromthe group consisting of FGF1, FGF2, FGF3, FGF4, FGF5, FGF6, FGF7, FGF8,FGF9, FGF10, FGF11, FGF12, FGF13, FGF14, FGF15, FGF16, FGF17, FGF18,FGF19, FGF20, FGF21, FGF22 and FGF23. In some embodiments, “FGF familygrowth factor,” “a fibroblast growth factor” or “member of thefibroblast growth factor family” means any growth factor having homologyand/or function similar to a known member of the fibroblast growthfactor family.

As used herein, “expression” refers to the production of a material orsubstance as well as the level or amount of production of a material orsubstance. Thus, determining the expression of a specific marker refersto detecting either the relative or absolute amount of the marker thatis expressed or simply detecting the presence or absence of the marker.

As used herein, “marker” refers to any molecule that can be observed ordetected. For example, a marker can include, but is not limited to, anucleic acid, such as a transcript of a specific gene, a polypeptideproduct of a gene, a non-gene product polypeptide, a glycoprotein, acarbohydrate, a glycolipid, a lipid, a lipoprotein or a small molecule(for example, molecules having a molecular weight of less than 10,000amu).

For most markers described herein, the official Human GenomeOrganisation (HUGO) gene symbol is provided. Such symbols, which aredeveloped by the HUGO Gene Nomenclature Committee, provide uniqueabbreviations for each of the named human genes and gene products. Thesegene symbols are readily recognized and can easily be associated with acorresponding unique human gene and/or protein sequence by those ofordinary skill in the art.

In accordance with the HUGO designations, the following gene symbols aredefined as follows: GHRL—ghrelin; IAPP—islet amyloid polypeptide;INS—insulin; GCG—glucagon; ISL1—ISL1 transcription factor; PAX6—pairedbox gene 6; PAX4—paired box gene 4; NEUROG3—neurogenin 3 (NGN3);NKX2-2—NKX2 transcription factor related, locus 2 (NKX2.2); NKX6-1—NKX6transcription factor related, locus 1 (NKX6.1); IPF1—insulin promoterfactor 1 (PDX1); ONECUT1—one cut domain, family member 1 (HNF6);HLXB9—homeobox B9 (HB9); TCF2—transcription factor 2, hepatic (HNF1b);FOXA1—forkhead box A1; HGF—hepatocyte growth factor; IGF1—insulin-likegrowth factor 1; POU5F1—POU domain, class 5, transcription factor 1(OCT4); NANOG—Nanog homeobox; SOX2—SRY (sex determining region Y)-box 2;CDH1—cadherin 1, type 1, E-cadherin (ECAD); T—brachyury homolog (BRACH);FGF4—fibroblast growth factor 4; WNT3—wingless-type MMTV integrationsite family, member 3; SOX17—SRY (sex determining region Y)-box 17;GSC—goosecoid; CER1—(cerberus 1, cysteine knot superfamily, homolog(CER); CXCR4—chemokine (C-X-C motif) receptor 4; FGF17—fibroblast growthfactor 17; FOXA2—forkhead box A2; SOX7—SRY (sex determining regionY)-box 7; SOX1—SRY (sex determining region Y)-box 1;AFP—alpha-fetoprotein; SPARC—secreted protein, acidic, cysteine-rich(osteonectin); and THBD—thrombomodulin (TM), NCAM—neural cell adhesionmolecule; SYP—synaptophysin; ZIC1—Zic family member 1;NEF3—neurofilament 3 (NFM); SST—somatostatin; MAFA—v-mafmusculoaponeurotic fibrosarcoma oncogene homolog A; MAFB—v-mafmusculoaponeurotic fibrosarcoma oncogene homolog B; SYP—synaptophysin;CHGA—chromogranin A (parathyroid secretory protein 1).

The following provides the full gene names corresponding to non-HUGOgene symbols as well as other abbreviations that may be used herein:SS—somatostatin (SOM); PP—pancreatic polypeptide; C-peptide—connectingpeptide; Ex4—exendin 4; NIC—nicotinamide andDAPT—N—[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butylester; RA—retinoic acid; RPMI—Roswell Park Memorial Institute medium;CMRL—Connaught Medical Research Labs medium; FBS—fetal bovine serum;NBP10—NCAM binding protein 10; PTF1a—pancreas specific transcriptionfactor 1a.

The terms fibroblast growth factor 7 (FGF7) and keritinocyte growthfactor (KGF) are synonymous.

As used herein, the term “label” refers to, for example, radioactive,fluorescent, biological or enzymatic tags or labels of standard use inthe art. A label can be conjugated, or otherwise bound, to nucleicacids, polypeptides, such as antibodies, or small molecules. Forexample, oligonucleotides of the present invention can be labeledsubsequent to synthesis, by incorporating biotinylated dNTPs or rNTP, orsome similar means (e.g., photo-cross-linking a psoralen derivative ofbiotin to RNAs), followed by addition of labeled streptavidin (e.g.,phycoerythrin-conjugated streptavidin) or the equivalent. Alternatively,when fluorescently-labeled oligonucleotide probes are used, fluorescein,lissamine, phycoerythirin, rhodamine (Perkin Elmer Cetus), Cy2, Cy3,Cy3.5, Cy5, Cy5.5, Cy7, FluorX (Amersham) and others, can be attached tonucleic acids. Non-limiting examples of detectable labels that may beconjugated to polypeptides such as antibodies include but are notlimited to radioactive labels, such as ³H, ¹¹C, ¹⁴C, ¹⁸F, ³²P, ³⁵S,⁶⁴Cu, ⁷⁶Br, ⁸⁶Y, ⁹⁹Tc, ¹¹¹In, ¹²³I, ¹²⁵I, or ¹⁷⁷Lu, enzymes, such ashorseradish peroxidase, fluorophores, chromophores, chemiluminescentagents, chelating complexes, dyes, colloidal gold or latex particles.

Human Embryonic Stem Cells

A preferred method for deriving definitive endoderm cells and ultimatelyendocrine precursor cells and/or pancreatic islet hormone-expressingcells utilizes human embryonic stem cells as the starting material. Suchpluripotent cells can be cells that originate from the morula, embryonicinner cell mass or those obtained from embryonic gonadal ridges. Humanembryonic stem cells can be maintained in culture in a pluripotent statewithout substantial differentiation using methods that are known in theart. Such methods are described, for example, in U.S. Pat. Nos.5,453,357, 5,670,372, 5,690,926 5,843,780, 6,200,806 and 6,251,671 thedisclosures of which are incorporated herein by reference in theirentireties.

In some processes, hESCs are maintained on a feeder layer. In suchprocesses, any feeder layer which allows hESCs to be maintained in apluripotent state can be used. One commonly used feeder layer for thecultivation of human embryonic stem cells is a layer of mousefibroblasts. More recently, human fibroblast feeder layers have beendeveloped for use in the cultivation of hESCs (see US Patent ApplicationNo. 2002/0072117, the disclosure of which is incorporated herein byreference in its entirety). Alternative processes permit the maintenanceof pluripotent hESC without the use of a feeder layer. Methods ofmaintaining pluripotent hESCs under feeder-free conditions have beendescribed in US Patent Application No. 2003/0175956, the disclosure ofwhich is incorporated herein by reference in its entirety.

The human embryonic stem cells used herein can be maintained in cultureeither with or without serum. In some embryonic stem cell maintenanceprocedures, serum replacement is used. In others, serum free culturetechniques, such as those described in US Patent Application No.2003/0190748, the disclosure of which is incorporated herein byreference in its entirety, are used.

Stem cells are maintained in culture in a pluripotent state by routinepassage until it is desired that they be differentiated into definitiveendoderm then ultimately to endocrine precursor cells and/or pancreaticislet hormone-expressing cells.

Production of Definitive Endoderm

In some processes, differentiation to definitive endoderm is achieved byproviding to the stem cell culture a growth factor of the TGFβsuperfamily in an amount sufficient to promote differentiation todefinitive endoderm. Growth factors of the TGFβ superfamily which areuseful for the production of definitive endoderm are selected from theNodal/Activin or BMP subgroups. In some preferred differentiationprocesses, the growth factor is selected from the group consisting ofNodal, activin A, activin B and BMP4. Additionally, the growth factorWnt3a and other Wnt family members are useful for the production ofdefinitive endoderm cells. In certain differentiation processes,combinations of any of the above-mentioned growth factors can be used.

With respect to some of the processes for the differentiation ofpluripotent stem cells to definitive endoderm cells, the above-mentionedgrowth factors are provided to the cells so that the growth factors arepresent in the cultures at concentrations sufficient to promotedifferentiation of at least a portion of the stem cells to definitiveendoderm cells. In some processes, the above-mentioned growth factorsare present in the cell culture at a concentration of at least about 5ng/ml, at least about 10 ng/ml, at least about 25 ng/ml, at least about50 ng/ml, at least about 75 ng/ml, at least about 100 ng/ml, at leastabout 200 ng/ml, at least about 300 ng/ml, at least about 400 ng/ml, atleast about 500 ng/ml, at least about 1000 ng/ml, at least about 2000ng/ml, at least about 3000 ng/ml, at least about 4000 ng/ml, at leastabout 5000 ng/ml or more than about 5000 ng/ml.

In certain processes for the differentiation of pluripotent stem cellsto definitive endoderm cells, the above-mentioned growth factors areremoved from the cell culture subsequent to their addition. For example,the growth factors can be removed within about one day, about two days,about three days, about four days, about five days, about six days,about seven days, about eight days, about nine days or about ten daysafter their addition. In a preferred process, the growth factors areremoved about four days after their addition.

Cultures of definitive endoderm cells can be produced from embryonicstem cells in medium containing reduced serum or no serum. Under certainculture conditions, serum concentrations can range from about 0.05% v/vto about 20% v/v. For example, in some differentiation processes, theserum concentration of the medium can be less than about 0.05% (v/v),less than about 0.1% (v/v), less than about 0.2% (v/v), less than about0.3% (v/v), less than about 0.4% (v/v), less than about 0.5% (v/v), lessthan about 0.6% (v/v), less than about 0.7% (v/v), less than about 0.8%(v/v), less than about 0.9% (v/v), less than about 1% (v/v), less thanabout 2% (v/v), less than about 3% (v/v), less than about 4% (v/v), lessthan about 5% (v/v), less than about 6% (v/v), less than about 7% (v/v),less than about 8% (v/v), less than about 9% (v/v), less than about 10%(v/v), less than about 15% (v/v) or less than about 20% (v/v). In someprocesses, definitive endoderm cells are grown without serum or withoutserum replacement. In still other processes, definitive endoderm cellsare grown in the presence of B27. In such processes, the concentrationof B27 supplement can range from about 0.1% v/v to about 20% v/v. Inother embodiments, the definitive endoderm cells are grown in theabsence of B27.

In some processes for differentiating human definitive endoderm cellsfrom hESCs, differentiation is initiated in the absence of serum and inthe absence of insulin and/or insulin-like growth factor. During thecourse of differentiation, the serum concentration may be graduallyincreased in order to promote adequate cell survival. In preferredembodiments, differentiation of hESCs to definitive endoderm cells isinitiated in the absence of serum and in the absence of any supplementcomprising insulin or insulin-like growth factors. The absence of serumand absence of supplement comprising insulin or insulin-like growthfactors is maintained for about 1 to about 2 days, after which, serum isgradually added to the differentiating cell culture over the course ofdifferentiation. In preferred embodiments, the concentration of serumdoes not exceed about 2% during the course of differentiation.

Definitive endoderm cell cultures and cell populations as well asdetailed processes for the production of definitive endoderm cells fromembryonic stem cells are further described in U.S. patent applicationSer. No. 11/021,618, entitled DEFINITIVE ENDODERM, filed Dec. 23, 2004,the disclosure of which is incorporated herein by reference in itsentirety.

Enrichment Isolation and/or Purification of Definitive Endoderm

In some embodiments of the processes described herein, definitiveendoderm cells are enriched, isolated and/or purified prior to furtherdifferentiation. In such embodiments, definitive endoderm cells can beenriched, isolated and/or purified using any known method. In preferredembodiments, the definitive endoderm cells are enriched, isolated and/orpurified using one or more of the methods described in U.S. patentapplication Ser. No. 11/021,618, entitled DEFINITIVE ENDODERM, filedDec. 23, 2004, and U.S. Provisional Patent Application No. 60/736,598,entitled MARKERS OF DEFINITIVE ENDODERM, filed Nov. 14, 2005, thedisclosures of which are incorporated herein by reference in theirentireties.

Compositions Comprising Definitive Endoderm Cells

Cell compositions produced by the above-described methods include cellcultures comprising definitive endoderm cells and cell populationsenriched in definitive endoderm cells. For example, cell cultures and/orcell populations that comprise definitive endoderm cells can beproduced, wherein at least about 50-99% of the cells in the cell cultureand/or cell population are definitive endoderm cells. Because theefficiency of the differentiation process can be adjusted by modifyingcertain parameters, which include but are not limited to, cell growthconditions, growth factor concentrations and the timing of culturesteps, the differentiation procedures described herein can result inabout 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%,about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about98%, about 99% or greater than about 99% conversion of pluripotent cellsto definitive endoderm. In processes in which isolation of definitiveendoderm cells is employed, for example, by using an affinity reagentthat binds to the CXCR4 receptor, a substantially pure definitiveendoderm cell population can be recovered. In embodiments where the cellcultures or cell populations comprise human feeder cells, the abovepercentages are calculated without respect to the human feeder cells inthe cell cultures or cell populations.

Production of PDX1-Positive Foregut Endoderm

Definitive endoderm cells can be specified toward pancreaticdifferentiation by further differentiation of these cells to producePDX1-positive foregut endoderm cells. In some of the differentiationprocesses described herein, cell cultures as well as enriched orpurified cell populations comprising definitive endoderm cells can beused for further differentiation to cell cultures and/or enriched cellpopulations comprising PDX1-positive foregut endoderm cells.

Typically, definitive endoderm cells are differentiated to PDX1-positiveforegut endoderm cells by providing to a cell culture comprisingSOX17-positive definitive endoderm cells a retinoid, such as retinoicacid (RA). In some of the differentiation processes, definitive endodermcells in culture are also provided with a member of the fibroblastgrowth factor family either prior to or about the same time as theaddition of RA. A preferred fibroblast growth factor is FGF-10. Inanother preferred process, the fibroblast growth factor comprises anyfibroblast growth factor or a ligand that stimulates or otherwiseinteracts with the fibroblast growth factor 2 receptor IIIb(FGFR2(IIIb). In even more preferred processes, the FGF family growthfactor is used in conjunction with a hedgehog pathway inhibitor. Apreferred hedgehog pathway inhibitor is KAAD-cyclopamine. In especiallypreferred differentiation processes, FGF-10 and/or KAAD-cyclopamine isprovided to a cell culture comprising PDX1-negative definitive endodermcells in the presence of RA. In certain processes, BMP4 may be includedwith FGF-10 and/or KAAD-cyclopamine in the presence of RA. In someprocesses, the retinoid is used in conjunction with a member of the TGFβsuperfamily of growth factors and/or Connaught Medical Research Labsmedium (CRML medium) (Invitrogen, Carlsbad, Calif.).

With respect to some of the embodiments of differentiation processesdescribed herein, the retinoid and/or a combination of theabove-mentioned differentiation factors are provided to the cells sothat these factors are present in the cell culture or cell population atconcentrations sufficient to promote differentiation of at least aportion of the definitive endoderm cell culture or cell population toPDX1-positive foregut endoderm cells.

In some processes, the retinoid is provided to the cells of a cellculture such that it is present at a concentration of at least about 1nM, at least about 0.01 μM, at least about 0.02 μM, at least about 0.04μM, at least about 0.08 μM, at least about 0.1 μM, at least about 0.2μM, at least about 0.3 μM, at least about 0.4 μM, at least about 0.5 μM,at least about 0.6 μM, at least about 0.7 μM, at least about 0.8 μM, atleast about 0.9 μM, at least about 1 μM, at least about 1.1 μM, at leastabout 1.2 μM, at least about 1.3 μM, at least about 1.4 μM, at leastabout 1.5 μM, at least about 1.6 μM, at least about 1.7 μM, at leastabout 1.8 μM, at least about 1.9 μM, at least about 2 μM, at least about2.1 μM, at least about 2.2 μM, at least about 2.3 μM, at least about 2.4μM, at least about 2.5 μM, at least about 2.6 μM, at least about 2.7 μM,at least about 2.8 μM, at least about 2.9 μM, at least about 3 μM, atleast about 3.5 μM, at least about 4 μM, at least about 4.5 μM, at leastabout 5 μM, at least about 10 μM, at least about 20 μM, at least about30 μM, at least about 40 μM or at least about 50 μM.

In other processes, FGF-10 is provided to the cells of a cell culturesuch that it is present at a concentration of at least about 1 ng/ml, atleast about 2 ng/ml, at least about 5 ng/ml, at least about 10 ng/ml, atleast about 25 ng/ml, at least about 50 ng/ml, at least about 75 ng/ml,at least about 100 ng/ml, at least about 200 ng/ml, at least about 300ng/ml, at least about 400 ng/ml, at least about 500 ng/ml, or at leastabout 1000 ng/ml. In other embodiments, when used alone or inconjunction with FGF-10, KAAD-cyclopamine can be provided at aconcentration of at least about 0.01 μM, at least about 0.02 μM, atleast about 0.04 μM, at least about 0.08 μM, at least about 0.1 μM, atleast about 0.2 μM, at least about 0.3 μM, at least about 0.4 μM, atleast about 0.5 μM, at least about 0.6 μM, at least about 0.7 μM, atleast about 0.8 μM, at least about 0.9 μM, at least about 1 μM, at leastabout 1.1 μM, at least about 1.2 μM, at least about 1.3 μM, at leastabout 1.4 μM, at least about 1.5 μM, at least about 1.6 μM, at leastabout 1.7 μM, at least about 1.8 μM, at least about 1.9 μM, at leastabout 2 μM, at least about 2.1 μM, at least about 2.2 μM, at least about2.3 μM, at least about 2.4 μM, at least about 2.5 μM, at least about 2.6μM, at least about 2.7 μM, at least about 2.8 μM, at least about 2.9 μM,at least about 3 μM, at least about 3.5 μM, at least about 4 μM, atleast about 4.5 μM, at least about 5 μM, at least about 10 μM, at leastabout 20 μM, at least about 30 μM, at least about 40 μM or at leastabout 50 μM. In some embodiments of the present invention, a fibroblastgrowth factor or a ligand that stimulates or otherwise interacts withthe fibroblast growth factor 2 receptor IIIb (FGFR2(IIIb) is providedeither alone or in combination with the hedgehog pathway inhibitor.

In a preferred process for the production of a population ofPDX1-positive foregut endoderm cells from definitive endoderm cells, acell culture or an enriched cell population of definitive endoderm cellsis provided with 50 ng/ml of FGF-10 and 0.2 μM KAAD-cyclopamine in CMRLmedium in the presence of 2 μM RA.

In some processes described herein, activin A and/or activin B isprovided to the cell culture along with the retinoid and/or thefibroblast growth factor and the hedgehog inhibitor. For example, insuch processes, activin A and/or activin B is provided to the cellculture at a concentration of at least about 5 ng/ml, at least about 10ng/ml, at least about 25 ng/ml, at least about 50 ng/ml, at least about75 ng/ml, at least about 100 ng/ml, at least about 200 ng/ml, at leastabout 300 ng/ml, at least about 400 ng/ml, at least about 500 ng/ml, orat least about 1000 ng/ml.

In some processes, the differentiation factors and/or CRML medium isprovided to the definitive endoderm cells at about three days, at aboutfour days, at about five days, at about six days, at about seven days,at about eight days, at about nine days, at about ten days or at aboutgreater than ten days subsequent to the initiation of differentiationfrom hESCs. In preferred processes, differentiation factors and/or CRMLmedium is provided to the definitive endoderm cells at about five dayssubsequent to the initiation of differentiation from hESCs.

In certain processes described herein, the above-mentioneddifferentiation factors are removed from the cell culture subsequent totheir addition. For example, the above-mentioned differentiation factorscan be removed within about one day, about two days, about three days,about four days, about five days, about six days, about seven days,about eight days, about nine days or about ten days after theiraddition.

Cultures of PDX1-positive foregut endoderm cells can be differentiatedand further grown in a medium containing reduced or no serum. Serumconcentrations can range from about 0.05% (v/v) to about 20% (v/v). Insome processes, dorsal PDX1-positive foregut endoderm cells are grownwith serum replacement. For example, in certain processes, the serumconcentration of the medium can be less than about 0.05% (v/v), lessthan about 0.1% (v/v), less than about 0.2% (v/v), less than about 0.3%(v/v), less than about 0.4% (v/v), less than about 0.5% (v/v), less thanabout 0.6% (v/v), less than about 0.7% (v/v), less than about 0.8%(v/v), less than about 0.9% (v/v), less than about 1% (v/v), less thanabout 2% (v/v), less than about 3% (v/v), less than about 4% (v/v), lessthan about 5% (v/v), less than about 6% (v/v), less than about 7% (v/v),less than about 8% (v/v), less than about 9% (v/v), less than about 10%(v/v), less than about 15% (v/v) or less than about 20% (v/v). Incertain processes described herein, the differentiation medium does notinclude serum, serum replacement or any supplement comprising insulin orinsulin-like growth factors.

In certain processes, PDX1-positive foregut endoderm cells are grown inthe presence of B27. In such differentiation processes, B27 can beprovided to the culture medium in concentrations ranging from about 0.1%(v/v) to about 20% (v/v) or in concentrations greater than about 20%(v/v). In certain processes, the concentration of B27 in the medium isabout 0.1% (v/v), about 0.2% (v/v), about 0.3% (v/v), about 0.4% (v/v),about 0.5% (v/v), about 0.6% (v/v), about 0.7% (v/v), about 0.8% (v/v),about 0.9% (v/v), about 1% (v/v), about 2% (v/v), about 3% (v/v), about4% (v/v), about 5% (v/v), about 6% (v/v), about 7% (v/v), about 8%(v/v), about 9% (v/v), about 10% (v/v), about 15% (v/v) or about 20%(v/v). Alternatively, the concentration of the added B27 supplement canbe measured in terms of multiples of the strength of a commerciallyavailable B27 stock solution. For example, B27 is available fromInvitrogen (Carlsbad, Calif.) as a 50× stock solution. Addition of asufficient amount of this stock solution to a sufficient volume ofgrowth medium produces a medium supplemented with the desired amount ofB27. For example, the addition of 10 ml of 50×B27 stock solution to 90ml of growth medium would produce a growth medium supplemented with5×B27. The concentration of B27 supplement in the medium can be about0.1×, about 0.2×, about 0.3×, about 0.4×, about 0.5×, about 0.6×, about0.7×, about 0.8×, about 0.9×, about 1×, about 1.1×, about 1.2×, about1.3×, about 1.4×, about 1.5×, about 1.6×, about 1.7×, about 1.8×, about1.9×, about 2×, about 2.5×, about 3×, about 3.5×, about 4×, about 4.5×,about 5×, about 6×, about 7×, about 8×, about 9×, about 10×, about 11×,about 12×, about 13×, about 14×, about 15×, about 16×, about 17×, about18×, about 19×, about 20× and greater than about 20×.

In some processes for the differentiation of PDX1-positive foregutendoderm cells from definitive endoderm cells, the definitive endodermcells are differentiated so as to be biased towards furtherdifferentiation to either dorsal pancreatic bud or ventral pancreaticbud as described in U.S. Provisional Patent Application No. 60/730,917,entitled PDX1-EXPRESSING DORSAL AND VENTRAL FOREGUT ENDODERM, filed Oct.27, 2005, the disclosure of which is incorporated herein by reference inits entirety. Additional detailed methods of producing PDX1-positiveforegut endoderm cells can be found in U.S. patent application Ser. No.11/115,868, entitled PDX1 EXPRESSING ENDODERM, filed Apr. 26, 2005, thedisclosure of which is incorporated herein by reference in its entirety.

Enrichment, Isolation and/or Purification of PDX1-Positive ForegutEndoderm

In some embodiments of the processes described herein, PDX1-positiveforegut endoderm cells are enriched, isolated and/or purified prior tofurther differentiation. In such embodiments, PDX1-positive foregutendoderm cells can be enriched, isolated and/or purified using any knownmethod. In preferred embodiments, the PDX1-positive foregut endodermcells are enriched, isolated and/or purified using one or more of themethods described in U.S. patent application Ser. No. 11/115,868,entitled PDX1 EXPRESSING ENDODERM, filed Apr. 26, 2005 and U.S.Provisional Patent Application No. 60/730,917, entitled PDX1-EXPRESSINGDORSAL AND VENTRAL FOREGUT ENDODERM, filed Oct. 27, 2005, thedisclosures of which are incorporated herein by reference in theirentireties.

Compositions Comprising PDX1-Positive Foregut Endoderm Cells

Cell compositions produced by the above-described methods include cellcultures comprising PDX1-positive foregut endoderm cells and cellpopulations enriched in PDX1-positive foregut endoderm cells. Forexample, cell cultures and/or cell populations that comprisePDX1-positive foregut endoderm cells can be produced, wherein at leastabout 50-99% of the cells in the cell culture and/or cell population arePDX1-positive foregut endoderm cells. Because the efficiency of thedifferentiation process can be adjusted by modifying certain parameters,which include but are not limited to, cell growth conditions, growthfactor concentrations and the timing of culture steps, thedifferentiation procedures described herein can result in about 5%,about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%,about 75%, about 80%, about 85%, about 90%, about 95%, about 98%, about99% or greater than about 99% conversion of pluripotent cells toPDX1-positive foregut endoderm. In processes in which isolation ofPDX1-positive foregut endoderm cells is employed, a substantially purePDX1-positive foregut endoderm cell population can be recovered. Inembodiments where the cell cultures or cell populations comprise humanfeeder cells, the above percentages are calculated without respect tothe human feeder cells in the cell cultures or cell populations.

Production of Endocrine Precursor Cells

Some embodiments of the present invention relate to methods of producingendocrine precursor cells starting from hESCs. As described above,endocrine precursor cells can be produced by first differentiating hESCsto produce definitive endoderm cells then further differentiating thedefinitive endoderm cells to produce PDX1-positive foregut endodermcells. In such embodiments, PDX1-positive foregut endoderm cells arefurther differentiated to multipotent endocrine precursor cells, whichare capable of differentiating into human pancreatic islethormone-expressing cells.

In one embodiment of the present invention, PDX1-positive foregutendoderm cells are differentiated to endocrine precursor cells bycontinuing the incubation of PDX1-positive foregut endoderm cells in thepresence of a retinoid, such as retinoic acid, for an amount of timesufficient to produce endocrine precursor cells. In some embodiment, theamount of time sufficient for the production of endocrine precursorcells ranges from about 1 hour to about 10 days subsequent to theexpression of the PDX1 marker in a portion of the cells in the cellculture. In some embodiments, the retinoid is maintained in the cellculture for about 1 hour, about 2 hours, about 4 hours, about 6 hours,about 8 hours, about 10 hours, about 12 hours, about 16 hours, about 1day, about 2 days, about 3 days, about 4 days, about 5 days, about 6days, about 7 days, about 8 days, about 9 days, about 10 days or greaterthan about 10 days subsequent to the expression of the PDX1 marker in aportion of the cells in the cell culture.

In some processes described herein, the concentration of retinoid usedto differentiate PDX1-positive foregut endoderm cells in the cellculture or cell population to endocrine precursor cells ranges fromabout 1 nM to about 100 μM. In some processes, the retinoid is providedto the cells of a cell culture such that it is present at aconcentration of at least about 1 nM, at least about 0.01 μM, at leastabout 0.02 μM, at least about 0.04 μM, at least about 0.08 μM, at leastabout 0.1 μM, at least about 0.2 μM, at least about 0.3 μM, at leastabout 0.4 μM, at least about 0.5 μM, at least about 0.6 μM, at leastabout 0.7 μM, at least about 0.8 μM, at least about 0.9 μM, at leastabout 1 μM, at least about 1.1 μM, at least about 1.2 μM, at least about1.3 μM, at least about 1.4 μM, at least about 1.5 μM, at least about 1.6μM, at least about 1.7 μM, at least about 1.8 μM, at least about 1.9 μM,at least about 2 μM, at least about 2.1 μM, at least about 2.2 μM, atleast about 2.3 μM, at least about 2.4 μM, at least about 2.5 μM, atleast about 2.6 μM, at least about 2.7 μM, at least about 2.8 μM, atleast about 2.9 μM, at least about 3 μM, at least about 3.5 μM, at leastabout 4 μM, at least about 4.5 μM, at least about 5 μM, at least about10 μM, at least about 20 μM, at least about 30 μM, at least about 40 μM,at least about 50 μM, at least about 75 μM or at least about 100 μM.

In some preferred embodiments of the present invention, differentiationfrom PDX1-positive foregut endoderm cells to pancreatic endocrineprecursor cells is mediated by providing a cell culture or cellpopulation comprising human PDX1-positive foregut endoderm cells with agamma secretase inhibitor. In a preferred embodiment, the gammasecretase inhibitor isN—[N-(3,5-Diflurophenacetyl-L-alanyl)]-S-phenylglycine t-Butyl Ester(DAPT).

In other embodiments of the present invention, the gamma secretaseinhibitor is provided at the start of the differentiation process, forexample, at the hESC stage, and remains in the cell culture throughoutthe differentiation to pancreatic islet hormone-expressing cells. Instill other embodiments, the gamma secretase inhibitor is added tosubsequent to the initiation of differentiation but prior todifferentiation to the PDX1-positive foregut endoderm stage. Inpreferred embodiments, the gamma secretase inhibitor is provided to thecell culture or cell population at about the same time as providing thedifferentiation factors which promote the conversion of definitiveendoderm to PDX1-positive endoderm. In other preferred embodiments, thegamma secretase inhibitor is provided to the cell culture or cellpopulation after a substantial portion of the cells in the cell cultureor cell population have differentiated to PDX1-positive foregut endodermcells.

With respect to some embodiments regarding the differentiation ofPDX1-positive foregut endoderm cells to endocrine precursor cells, thegamma secretase inhibitor is provided to the cells so that it is presentin the cell culture or cell population at concentrations sufficient topromote differentiation of at least a portion of the PDX1-positive cellsto endocrine precursor cells. In some embodiments, the gamma secretaseinhibitor is present in the cell culture or cell population at aconcentration ranging from about 0.01 μM to about 1000 μM. In preferredembodiments, the gamma secretase inhibitor is present in the cellculture or cell population at a concentration ranging from about 0.1 μMto about 100 μM. In more preferred embodiments, the gamma secretaseinhibitor is present in the cell culture or cell population at aconcentration ranging from about 1 μM to about 10 μM. In otherembodiments, the gamma secretase inhibitor is present in the cellculture or cell population at a concentration of at least about 0.01 μM,at least about 0.02 μM, at least about 0.04 μM, at least about 0.08 μM,at least about 0.1 μM, at least about 0.2 μM, at least about 0.3 μM, atleast about 0.4 μM, at least about 0.5 μM, at least about 0.6 μM, atleast about 0.7 μM, at least about 0.8 μM, at least about 0.9 μM, atleast about 1 μM, at least about 1.1 μM, at least about 1.2 μM, at leastabout 1.3 μM, at least about 1.4 μM, at least about 1.5 μM, at leastabout 1.6 μM, at least about 1.7 μM, at least about 1.8 μM, at leastabout 1.9 μM, at least about 2 μM, at least about 2.1 μM, at least about2.2 μM, at least about 2.3 μM, at least about 2.4 μM, at least about 2.5μM, at least about 2.6 μM, at least about 2.7 μM, at least about 2.8 μM,at least about 2.9 μM, at least about 3 μM, at least about 3.5 μM, atleast about 4 μM, at least about 4.5 μM, at least about 5 μM, at leastabout 10 μM, at least about 20 μM, at least about 30 μM, at least about40 μM, at least about 50 μM, at least about 60 μM, at least about 70 μM,at least about 80 μM, at least about 90 μM, at least about 100 μM, atleast about 250 μM, at least about 500 μM, at least about 750 μM or atleast about 1000 μM.

In certain embodiments of the processes for producing endocrineprecursor cells as described herein, the gamma secretase inhibitor isprovided after one or more previously provided differentiation factorshave been removed from the cell cultures. For example, the one or morepreviously provided differentiation factors can be removed about 1 day,about 2 days, about 3 days, about 4 days, about 5 days, about 6 days,about 7 days, about 8 days, about 9 days, about 10 days or more thanabout 10 days prior to the addition of the gamma secretase inhibitor. Inother embodiments, the gamma secretase inhibitor is provided to cellcultures or cell populations comprising one or more differentiationfactors that were previously provided or provided at about the same timeas the gamma secretase inhibitor. In preferred embodiments,differentiation factors that were previously provided or provided atabout the same time as the gamma secretase inhibitor include, but arenot limited to, FGF-10, KAAD-cyclopamine, activin A, activin B, BMP4and/or RA.

In some embodiments of the invention described herein, exendin 4 isprovided to the differentiating cell culture or cell population at aboutthe same time as the gamma secretase inhibitor. In certain embodiments,exendin 4 is provided so as to be in present in the cell culture or cellpopulation at a concentration of at least about 0.1 ng/ml, at leastabout 0.2 ng/ml, at least about 0.3 ng/ml, at least about 0.4 ng/ml, atleast about 0.5 ng/ml, at least about 0.6 ng/ml, at least about 0.7ng/ml, at least about 0.8 ng/ml, at least about 0.9 ng/ml, at leastabout 1 ng/ml, at least about 5 ng/ml, at least about 10 ng/ml, at leastabout 15 ng/ml, at least about 20 ng/ml, at least about 25 ng/ml, atleast about 30 ng/ml, at least about 35 ng/ml, at least about 40 ng/ml,at least about 45 ng/ml, at least about 50 ng/ml, at least about 55ng/ml, at least about 60 ng/ml, at least about 65 ng/ml, at least about70 ng/ml, at least about 75 ng/ml, at least about 80 ng/ml, at leastabout 85 ng/ml, at least about 90 ng/ml, at least about 95 ng/ml, atleast about 100 ng/ml, at least about 150 ng/ml, at least about 200ng/ml, at least about 250 ng/ml, at least about 300 ng/ml, at leastabout 350 ng/ml, at least about 400 ng/ml, at least about 450 ng/ml, atleast about 500 ng/ml, at least about 550 ng/ml, at least about 600ng/ml, at least about 650 ng/ml, at least about 700 ng/ml, at leastabout 750 ng/ml, at least about 800 ng/ml, at least about 850 ng/ml, atleast about 900 ng/ml, at least about 950 ng/ml or at least about 1000ng/ml.

In a preferred process for the production of endocrine precursor cellsfrom PDX1-positive foregut endoderm cells, a cell culture or cellpopulation of PDX1-positive foregut endoderm cells is provided with 3 μMDAPT and 40 ng/ml exendin 4. In especially preferred embodiments, thecells are differentiated in CMRL. In another especially preferredprocess, for the production of a endocrine precursor cells fromPDX1-positive foregut endoderm cells, a cell culture or cell populationof PDX1-positive foregut endoderm cells is provided with 3 μM DAPT and40 ng/ml exendin 4 in the presence of 2 μM RA.

In certain processes for producing endocrine precursor cells asdescribed herein, the above-mentioned differentiation factors areremoved from the cell culture or cell population subsequent to theiraddition. For example, the gamma secretase inhibitor and/or exendin 4can be removed within about one day, about two days, about three days,about four days, about five days, about six days, about seven days,about eight days, about nine days or about ten days after theiraddition. In some embodiments, the differentiation factors are notremoved from the cell culture.

Cultures of endocrine precursor cells can be produced in mediumcontaining reduced serum or no serum. Under certain culture conditions,serum concentrations can range from about 0.05% v/v to about 20% v/v.For example, in some differentiation processes, the serum concentrationof the medium can be less than about 0.05% (v/v), less than about 0.1%(v/v), less than about 0.2% (v/v), less than about 0.3% (v/v), less thanabout 0.4% (v/v), less than about 0.5% (v/v), less than about 0.6%(v/v), less than about 0.7% (v/v), less than about 0.8% (v/v), less thanabout 0.9% (v/v), less than about 1% (v/v), less than about 2% (v/v),less than about 3% (v/v), less than about 4% (v/v), less than about 5%(v/v), less than about 6% (v/v), less than about 7% (v/v), less thanabout 8% (v/v), less than about 9% (v/v), less than about 10% (v/v),less than about 15% (v/v) or less than about 20% (v/v). In someprocesses, endocrine precursor cells are grown without serum, withoutserum replacement and/or without any supplement containing insulin orinsulin-like growth factor. In still other processes, endocrineprecursor cells are grown in the presence of B27. In such processes, theconcentration of B27 supplement can range from about 0.1% v/v to about20% v/v. In other embodiments, the endocrine precursor cells are grownin the absence of B27.

Monitoring the Differentiation of PDX1-Positive Cells to EndocrinePrecursor Cells

The progression of PDX1-positive endoderm cells to endocrine precursorcells can be monitored by determining the expression of markerscharacteristic of endocrine precursor cells. In some processes, theexpression of certain markers is determined by detecting the presence orabsence of the marker. Alternatively, the expression of certain markerscan be determined by measuring the level at which the marker is presentin the cells of the cell culture or cell population. In such processes,the measurement of marker expression can be qualitative or quantitative.One method of quantitating the expression of markers that are producedby marker genes is through the use of quantitative PCR (Q-PCR). Methodsof performing Q-PCR are well known in the art. Other methods which areknown in the art can also be used to quantitate marker gene expression.For example, the expression of a marker gene product can be detected byusing antibodies specific for the marker gene product of interest. Incertain processes, the expression of marker genes characteristic ofendocrine precursor cells as well as the lack of significant expressionof marker genes characteristic of hESCs, definitive endoderm,PDX1-positive foregut endoderm, extraembryonic endoderm, mesoderm,ectoderm, immature pancreatic islet hormone-expressing cells or maturepancreatic islet hormone-expressing cells and/or other cell types isdetermined.

As described further in the Examples below, a reliable marker ofendocrine precursor cells is the NGN3 gene. As such, the endocrineprecursor cells produced by the processes described herein express theNGN3 marker gene, thereby producing the NGN3 gene product. Other markersof endocrine precursor cells are NKX2.2 and PAX4.

In some processes, the expression of genes indicative of hESCs,definitive endoderm cells and/or PDX1-positive foregut endoderm cells isalso monitored. For example, in some processes, the expression of AFP,SOX7, SOX1, ZIC1, and NFM are monitored. In some processes, theexpression of genes indicative of immature pancreatic islethormone-expressing cells and/or mature pancreatic islethormone-expressing cells is also monitored. For example, in someembodiments, the expression of MAFB, SYP, CHGA, INS, GCG, SST, GHRL andPAX6 is monitored.

It will be appreciated that NGN3, NKX2.2 and/or PAX4 marker expressionis induced over a range of different levels in endocrine precursor cellsdepending on the differentiation conditions. As such, in someembodiments described herein, the expression of the NGN3, NKX2.2 and/orPAX4 marker in endocrine precursor cells or cell populations is at leastabout 2-fold higher to at least about 10.000-fold higher than theexpression of the NGN3, NKX2.2 and/or PAX4 marker in non-endocrineprecursor cells or cell populations, for example pluripotent stem cells,definitive endoderm cells, PDX1-positive foregut endoderm cells,immature pancreatic islet hormone-expressing cells, mature pancreaticislet hormone-expressing cells, extraembryonic endoderm cells, mesodermcells and/or ectoderm cells. In other embodiments, the expression of theNGN3, NKX2.2 and/or PAX4 marker in endocrine precursor cells or cellpopulations is at least about 4-fold higher, at least about 6-foldhigher, at least about 8-fold higher, at least about 10-fold higher, atleast about 15-fold higher, at least about 20-fold higher, at leastabout 40-fold higher, at least about 80-fold higher, at least about100-fold higher, at least about 150-fold higher, at least about 200-foldhigher, at least about 500-fold higher, at least about 750-fold higher,at least about 1000-fold higher, at least about 2500-fold higher, atleast about 5000-fold higher, at least about 7500-fold higher or atleast about 10.000-fold higher than the expression of the NGN3, NKX2.2and/or PAX4 marker in non-endocrine precursor cells or cell populations,for example pluripotent stem cells, definitive endoderm cells,PDX1-positive foregut endoderm cells, immature pancreatic islethormone-expressing cells, mature pancreatic islet hormone-expressingcells, extraembryonic endoderm cells, mesoderm cells and/or ectodermcells. In some embodiments, the expression of the NGN3, NKX2.2 and/orPAX4 marker in endocrine precursor cells or cell populations isinfinitely higher than the expression of the NGN3, NKX2.2 and/or PAX4marker in non-endocrine precursor cells or cell populations, for examplepluripotent stem cells, definitive endoderm cells, PDX1-positive foregutendoderm cells, immature pancreatic islet hormone-expressing cells,mature pancreatic islet hormone-expressing cells, extraembryonicendoderm cells, mesoderm cells and/or ectoderm cells.

Enrichment, Isolation and/or Purification of Endocrine Precursor Cells

With respect to additional aspects of the present invention, endocrineprecursor cells can be enriched, isolated and/or purified. In someembodiments of the present invention, cell populations enriched,isolated and/or purified for endocrine precursor cells are produced byisolating such cells from cell cultures.

Endocrine precursor cells produced by any of the processes describedherein can be enriched, isolated and/or purified by using an affinitytag that is specific for such cells. Examples of affinity tags specificfor endocrine precursor cells are antibodies, antibody fragments,ligands or other binding agents that are specific to a marker molecule,such as a polypeptide, that is present on the cell surface of endocrineprecursor cells but which is not substantially present on other celltypes that would be found in a cell culture produced by the methodsdescribed herein. In some processes, an antibody which binds to NCAM isused as an affinity tag for the enrichment, isolation or purification ofendocrine precursor cells. In other processes, the NCAM ligand NBP10, orany other NCAM ligand now known or discovered in the future can also beused as affinity tags, for example, see Ronn, L. (2002) Eur J Neurosci.,16:1720-30, the disclosure of which is incorporated herein by referencein its entirety. Such molecules include, but are not limited to, NBP10fusions and NBP10 mimetics.

Methods for making antibodies and using them for cell isolation areknown in the art and such methods can be implemented for use with theantibodies and endocrine precursor cells described herein. In oneprocess, an antibody which binds to NCAM is attached to a magnetic beadand then allowed to bind to endocrine precursor cells in a cell culturewhich has been enzymatically treated to reduce intercellular andsubstrate adhesion. The cell/antibody/bead complexes are then exposed toa movable magnetic field which is used to separate bead-bound endocrineprecursor cells from unbound cells. Once the endocrine precursor cellsare physically separated from other cells in culture, the antibodybinding is disrupted and the cells are replated in appropriate tissueculture medium. If desired, the isolated cell compositions can befurther purified by using an alternate affinity-based method or byadditional rounds of enrichment using the same or different markers thatare specific for endocrine precursor cells.

Additional methods for obtaining enriched, isolated or purifiedendocrine precursor cell cultures or populations can also be used. Forexample, in some embodiments, the NCAM antibody is incubated with anendocrine precursor-containing cell culture that has been treated toreduce intercellular and substrate adhesion. (WE DON'T USE SECONDARYANTIBODIES. THE NCAM ANTIBODY IS DIRECTLY CONJUGATED TO EITHER PE, APC,OR FITC) The cells are then washed, centrifuged and resuspended. Thecell suspension is then incubated with a secondary antibody, such as anFITC-conjugated antibody that is capable of binding to the primaryantibody. The cells are then washed, centrifuged and resuspended inbuffer. The cell suspension is then analyzed and sorted using afluorescence activated cell sorter (FACS). NCAM-positive cells arecollected separately from NCAM-negative cells, thereby resulting in theisolation of such cell types. If desired, the isolated cell compositionscan be further purified by using an alternate affinity-based method orby additional rounds of sorting using the same or different markers thatare specific for endocrine precursor cells. Alternatively, isolated cellcompositions can be further purified by negatively sorting for a markerthat is present on most cells in the cell population other thanendocrine precursor cells.

In still other processes, endocrine precursor cells are enriched,isolated and/or purified using a ligand or other molecule that binds toNCAM. In some processes, the molecule is NBP10 or a fragment, fusion ormimetic thereof.

In some embodiments of the processes described herein, a nucleic acidencoding green fluorescent protein (GFP) or another nucleic acidencoding an expressible fluorescent marker gene (e.g., yellowfluorescent protein (YFP), luciferase or the like) is used to labelNCAM-positive cells. For example, in some embodiments, at least one copyof a nucleic acid encoding GFP or a biologically active fragment thereofis introduced into a pluripotent cell, preferably a human embryonic stemcell, downstream of the NCAM promoter, the NGN3 promoter, the PAX4promoter, or the promoter of any endocrine precursor cell-specific genesuch that the expression of the GFP gene product or biologically activefragment thereof is under control of the NCAM, NGN3, or PAX4 promoter.In some embodiments, the entire coding region of the nucleic acid, whichencodes NCAM, NGN3, or PAX4, is replaced by a nucleic acid encoding GFPor a biologically active fragment thereof. In other embodiments, thenucleic acid encoding GFP or a biologically active fragment thereof isfused in frame with at least a portion of the nucleic acid encodingNCAM, NGN3, or PAX4, thereby generating a fusion protein. In suchembodiments, the fusion protein retains a fluorescent activity similarto GFP.

Fluorescently marked cells, such as the above-described pluripotentcells, are differentiated to endocrine precursor cells as describedherein. Because endocrine precursor cells express the fluorescent markergene, whereas other cell types do not, endocrine precursor cells can beseparated from the other cell types. In some embodiments, cellsuspensions comprising a mixture of fluorescently-labeled endocrineprecursor cells and unlabeled non-endocrine precursor cells are sortedusing a FACS. Endocrine precursor cells are collected separately fromnon-fluorescing cells, thereby resulting in the isolation of endocrineprecursors. If desired, the isolated cell compositions can be furtherpurified by additional rounds of sorting using the same or differentmarkers that are specific for endocrine precursor cells.

In preferred processes, endocrine precursor cells are enriched, isolatedand/or purified from other non-endocrine precursor cells afterendodermal cell cultures are induced to differentiate towards theendocrine precursor lineage. It will be appreciated that theabove-described enrichment, isolation and purification procedures can beused with such cultures at any stage of differentiation.

In addition to the procedures just described, endocrine precursor cellsmay also be isolated by other techniques for cell isolation.Additionally, endocrine precursor cells may also be enriched or isolatedby methods of serial subculture in growth conditions which promote theselective survival or selective expansion of the endocrine precursorcells.

Using the methods described herein, enriched, isolated and/or purifiedpopulations of endocrine precursor cells and or tissues can be producedin vitro from pluripotent cell cultures or cell populations, such asstem cell cultures or populations, which have undergone at least somedifferentiation. In some methods, the cells undergo randomdifferentiation. In a preferred method, however, the cells are directedto differentiate primarily into endocrine precursor cells. Somepreferred enrichment, isolation and/or purification methods relate tothe in vitro production of endocrine precursor cells from humanembryonic stem cells.

Using the methods described herein, cell populations or cell culturescan be enriched in endocrine precursor cell content by at least about 2-to about 1000-fold as compared to untreated cell populations or cellcultures. In some embodiments, endocrine precursor cells can be enrichedby at least about 5- to about 500-fold as compared to untreated cellpopulations or cell cultures. In other embodiments, endocrine precursorcells can be enriched from at least about 10- to about 200-fold ascompared to untreated cell populations or cell cultures. In still otherembodiments, endocrine precursor cells can be enriched from at leastabout 20- to about 100-fold as compared to untreated cell populations orcell cultures. In yet other embodiments, endocrine precursor cells canbe enriched from at least about 40- to about 80-fold as compared tountreated cell populations or cell cultures. In certain embodiments,endocrine precursor cells can be enriched from at least about 2- toabout 20-fold as compared to untreated cell populations or cellcultures.

Compositions Comprising Endocrine Precursor Cells

Some embodiments of the present invention relate to cell compositions,such as cell cultures or cell populations, comprising endocrineprecursor cells, wherein the endocrine precursor cells are multipotentcells that can differentiate into cells of the endocrine system, such aspancreatic islet hormone-expressing cells. In accordance with certainembodiments, the endocrine precursor cells are mammalian cells, and in apreferred embodiment, such cells are human cells.

Other embodiments of the present invention relate to compositions, suchas cell cultures or cell populations, comprising endocrine precursorcells and cells that are less specifically differentiated than endocrineprecursor cells. In such embodiments, cells that are less specificallydifferentiated than endocrine precursor cells comprise less than about90%, less than about 85%, less than about 80%, less than about 75%, lessthan about 70%, less than about 65%, less than about 60%, less thanabout 55%, less than about 50%, less than about 45%, less than about40%, less than about 35%, less than about 30%, less than about 25%, lessthan about 20%, less than about 15%, less than about 12%, less thanabout 10%, less than about 8%, less than about 6%, less than about 5%,less than about 4%, less than about 3%, less than about 2% or less thanabout 1% of the total cells in the culture.

Other embodiments relate to compositions, such as cell cultures or cellpopulations, comprising endocrine precursor cells and cells that aremore specifically differentiated than endocrine precursor cells, such asimmature pancreatic islet hormone-expressing cells and/or maturepancreatic islet hormone-expressing cells. In such embodiments, cellsthat are more specifically differentiated than endocrine precursor cellscomprise less than about 90%, less than about 85%, less than about 80%,less than about 75%, less than about 70%, less than about 65%, less thanabout 60%, less than about 55%, less than about 50%, less than about45%, less than about 40%, less than about 35%, less than about 30%, lessthan about 25%, less than about 20%, less than about 15%, less thanabout 12%, less than about 10%, less than about 8%, less than about 6%,less than about 5%, less than about 4%, less than about 3%, less thanabout 2% or less than about 1% of the total cells in the culture.

Certain other embodiments of the present invention relate tocompositions, such as cell cultures or cell populations, comprisingendocrine precursor cells and cells of one or more cell types selectedfrom the group consisting of hESCs, pre-primitive streak cells,mesendoderm cells, definitive endoderm cells, PDX1-negative foregutendoderm cells, PDX1-positive foregut endoderm cells (PDX1-positivepancreatic endoderm cells) and mesoderm cells. In some embodiments,hESCs comprise less than about 25%, less than about 20%, less than about15%, less than about 10%, less than about 5%, less than about 4%, lessthan about 3%, less than about 2% or less than about 1% of the totalcells in the culture. In certain embodiments, pre-primitive streak cellscomprise less than about 25%, less than about 20%, less than about 15%,less than about 10%, less than about 5%, less than about 4%, less thanabout 3%, less than about 2% or less than about 1% of the total cells inthe culture. In other embodiments, mesendoderm cells comprise less thanabout 25%, less than about 20%, less than about 15%, less than about10%, less than about 5%, less than about 4%, less than about 3%, lessthan about 2% or less than about 1% of the total cells in the culture.In still other embodiments, definitive endoderm cells comprise less thanabout 90%, less than about 85%, less than about 80%, less than about75%, less than about 70%, less than about 65%, less than about 60%, lessthan about 55%, less than about 50%, less than about 45%, less thanabout 40%, less than about 35%, less than about 30%, less than about25%, less than about 20%, less than about 15%, less than about 12%, lessthan about 10%, less than about 8%, less than about 6%, less than about5%, less than about 4%, less than about 3%, less than about 2% or lessthan about 1% of the total cells in the culture. In yet otherembodiments, PDX1-negative foregut endoderm cells comprise less thanabout 90%, less than about 85%, less than about 80%, less than about75%, less than about 70%, less than about 65%, less than about 60%, lessthan about 55%, less than about 50%, less than about 45%, less thanabout 40%, less than about 35%, less than about 30%, less than about25%, less than about 20%, less than about 15%, less than about 12%, lessthan about 10%, less than about 8%, less than about 6%, less than about5%, less than about 4%, less than about 3%, less than about 2% or lessthan about 1% of the total cells in the culture. In certain embodiments,PDX1-positive foregut endoderm cells comprise less than about 90%, lessthan about 85%, less than about 80%, less than about 75%, less thanabout 70%, less than about 65%, less than about 60%, less than about55%, less than about 50%, less than about 45%, less than about 40%, lessthan about 35%, less than about 30%, less than about 25%, less thanabout 20%, less than about 15%, less than about 12%, less than about10%, less than about 8%, less than about 6%, less than about 5%, lessthan about 4%, less than about 3%, less than about 2% or less than about1% of the total cells in the culture. In still other embodiments,mesoderm cells comprise less than about 90%, less than about 85%, lessthan about 80%, less than about 75%, less than about 70%, less thanabout 65%, less than about 60%, less than about 55%, less than about50%, less than about 45%, less than about 40%, less than about 35%, lessthan about 30%, less than about 25%, less than about 20%, less thanabout 15%, less than about 12%, less than about 10%, less than about 8%,less than about 6%, less than about 5%, less than about 4%, less thanabout 3%, less than about 2% or less than about 1% of the total cells inthe culture.

Certain other embodiments of the present invention relate tocompositions, such as cell cultures or cell populations, comprisingendocrine precursor cells and cells of one or more cell types selectedfrom the group consisting of immature pancreatic islethormone-expressing cells and/or mature pancreatic hormone-expressingcells. In some embodiments, immature pancreatic islet hormone-expressingcells comprise less than about 25%, less than about 20%, less than about15%, less than about 10%, less than about 5%, less than about 4%, lessthan about 3%, less than about 2% or less than about 1% of the totalcells in the culture. In certain embodiments, mature pancreatic islethormone-expressing cells comprise less than about 25%, less than about20%, less than about 15%, less than about 10%, less than about 5%, lessthan about 4%, less than about 3%, less than about 2% or less than about1% of the total cells in the culture.

Additional embodiments of the present invention relate to compositions,such as cell cultures or cell populations, produced by the processesdescribed herein and which comprise endocrine precursor cells as themajority cell type. In some embodiments, the processes described hereinproduce cell cultures and/or cell populations comprising at least about99%, at least about 98%, at least about 97%, at least about 96%, atleast about 95%, at least about 94%, at least about 93%, at least about92%, at least about 91%, at least about 90%, at least about 89%, atleast about 88%, at least about 87%, at least about 86%, at least about85%, at least about 84%, at least about 83%, at least about 82%, atleast about 81%, at least about 80%, at least about 79%, at least about78%, at least about 77%, at least about 76%, at least about 75%, atleast about 74%, at least about 73%, at least about 72%, at least about71%, at least about 70%, at least about 69%, at least about 68%, atleast about 67%, at least about 66%, at least about 65%, at least about64%, at least about 63%, at least about 62%, at least about 61%, atleast about 60%, at least about 59%, at least about 58%, at least about57%, at least about 56%, at least about 55%, at least about 54%, atleast about 53%, at least about 52%, at least about 51% or at leastabout 50% endocrine precursor cells. In preferred embodiments, the cellsof the cell cultures or cell populations comprise human cells. In otherembodiments, the processes described herein produce cell cultures orcell populations comprising at least about 50%, at least about 45%, atleast about 40%, at least about 35%, at least about 30%, at least about25%, at least about 24%, at least about 23%, at least about 22%, atleast about 21%, at least about 20%, at least about 19%, at least about18%, at least about 17%, at least about 16%, at least about 15%, atleast about 14%, at least about 13%, at least about 12%, at least about11%, at least about 10%, at least about 9%, at least about 8%, at leastabout 7%, at least about 6%, at least about 5%, at least about 4%, atleast about 3%, at least about 2% or at least about 1% endocrineprecursor cells. In preferred embodiments, the cells of the cellcultures or cell populations comprise human cells. In some embodiments,the percentage of endocrine precursor cells in the cell cultures orpopulations is calculated without regard to the feeder cells remainingin the culture.

Still other embodiments of the present invention relate to compositions,such as cell cultures or cell populations, comprising mixtures ofendocrine precursor cells and PDX1-positive foregut endoderm cells. Forexample, cell cultures or cell populations comprising at least about 5endocrine precursor cells for about every 95 PDX1-positive foregutendoderm cells can be produced. In other embodiments, cell cultures orcell populations comprising at least about 95 endocrine precursor cellsfor about every 5 PDX1-positive foregut endoderm cells can be produced.Additionally, cell cultures or cell populations comprising other ratiosof endocrine precursor cells to PDX1-positive foregut endoderm cells arecontemplated. For example, compositions comprising at least about 1endocrine precursor cell for about every 1,000,000 PDX1-positive foregutendoderm cells, at least about 1 endocrine precursor cell for aboutevery 100,000 PDX1-positive foregut endoderm cells, at least about 1endocrine precursor cell for about every 10,000 PDX1-positive foregutendoderm cells, at least about 1 endocrine precursor cell for aboutevery 1000 PDX1-positive foregut endoderm cells, at least about 1endocrine precursor cell for about every 500 PDX1-positive foregutendoderm cells, at least about 1 endocrine precursor cell for aboutevery 100 PDX1-positive foregut endoderm cells, at least about 1endocrine precursor cell for about every 10 PDX1-positive foregutendoderm cells, at least about 1 endocrine precursor cell for aboutevery 5 PDX1-positive foregut endoderm cells, at least about 1 endocrineprecursor cell for about every 4 PDX1-positive foregut endoderm cells,at least about 1 endocrine precursor cell for about every 2PDX1-positive foregut endoderm cells, at least about 1 endocrineprecursor cell for about every 1 PDX1-positive foregut endoderm cell, atleast about 2 endocrine precursor cells for about every 1 PDX1-positiveforegut endoderm cell, at least about 4 endocrine precursor cells forabout every 1 PDX1-positive foregut endoderm cell, at least about 5endocrine precursor cells for about every 1 PDX1-positive foregutendoderm cell, at least about 10 endocrine precursor cells for aboutevery 1 PDX1-positive foregut endoderm cell, at least about 20 endocrineprecursor cells for about every 1 PDX1-positive foregut endoderm cell,at least about 50 endocrine precursor cells for about every 1PDX1-positive foregut endoderm cell, at least about 100 endocrineprecursor cells for about every 1 PDX1-positive foregut endoderm cell,at least about 1000 endocrine precursor cells for about every 1PDX1-positive foregut endoderm cell, at least about 10,000 endocrineprecursor cells for about every 1 PDX1-positive foregut endoderm cell,at least about 100,000 endocrine precursor cells for about every 1PDX1-positive foregut endoderm cell and at least about 1,000,000endocrine precursor cells for about every 1 PDX1-positive foregutendoderm cell are contemplated.

Still other embodiments of the present invention relate to compositions,such as cell cultures or cell populations, comprising mixtures ofendocrine precursor cells and immature pancreatic islethormone-expressing and/or mature pancreatic islet hormone-expressingcells. For example, cell cultures or cell populations comprising atleast about 5 endocrine precursor cells for about every 95 immaturepancreatic islet hormone-expressing and/or mature pancreatic islethormone-expressing cells can be produced. In other embodiments, cellcultures or cell populations comprising at least about 95 endocrineprecursor cells for about every 5 immature pancreatic islethormone-expressing and/or mature pancreatic islet hormone-expressingcells can be produced. Additionally, cell cultures or cell populationscomprising other ratios of endocrine precursor cells to immaturepancreatic islet hormone-expressing and/or mature pancreatic islethormone-expressing cells are contemplated. For example, compositionscomprising at least about 1 endocrine precursor cell for about every1,000,000 immature pancreatic islet hormone-expressing and/or maturepancreatic islet hormone-expressing cells, at least about 1 endocrineprecursor cell for about every 100,000 immature pancreatic islethormone-expressing and/or mature pancreatic islet hormone-expressingcells, at least about 1 endocrine precursor cell for about every 10,000immature pancreatic islet hormone-expressing and/or mature pancreaticislet hormone-expressing cells, at least about 1 endocrine precursorcell for about every 1000 immature pancreatic islet hormone-expressingand/or mature pancreatic islet hormone-expressing cells, at least about1 endocrine precursor cell for about every immature pancreatic islethormone-expressing and/or mature pancreatic islet hormone-expressingcells, at least about 1 endocrine precursor cell for about every 100immature pancreatic islet hormone-expressing and/or mature pancreaticislet hormone-expressing cells, at least about 1 endocrine precursorcell for about every 10 immature pancreatic islet hormone-expressingand/or mature pancreatic islet hormone-expressing cells, at least about1 endocrine precursor cell for about every 5 immature pancreatic islethormone-expressing and/or mature pancreatic islet hormone-expressingcells, at least about 1 endocrine precursor cell for about every 4immature pancreatic islet hormone-expressing and/or mature pancreaticislet hormone-expressing cells, at least about 1 endocrine precursorcell for about every 2 immature pancreatic islet hormone-expressingand/or mature pancreatic islet hormone-expressing cells, at least about1 endocrine precursor cell for about every 1 immature pancreatic islethormone-expressing cell and/or mature pancreatic islethormone-expressing cell, at least about 2 endocrine precursor cells forabout every 1 immature pancreatic islet hormone-expressing cell and/ormature pancreatic islet hormone-expressing cell, at least about 4endocrine precursor cells for about every 1 immature pancreatic islethormone-expressing cell and/or mature pancreatic islethormone-expressing cell, at least about 5 endocrine precursor cells forabout every 1 immature pancreatic islet hormone-expressing cell and/ormature pancreatic islet hormone-expressing cell, at least about 10endocrine precursor cells for about every immature pancreatic islethormone-expressing cell and/or mature pancreatic islethormone-expressing cell, at least about 20 endocrine precursor cells forabout every 1 immature pancreatic islet hormone-expressing cell and/ormature pancreatic islet hormone-expressing cell, at least about 50endocrine precursor cells for about every 1 immature pancreatic islethormone-expressing cell and/or mature pancreatic islethormone-expressing cell, at least about 100 endocrine precursor cellsfor about every 1 immature pancreatic islet hormone-expressing celland/or mature pancreatic islet hormone-expressing cell, at least about1000 endocrine precursor cells for about every 1 immature pancreaticislet hormone-expressing cell and/or mature pancreatic islethormone-expressing cell, at least about 10,000 endocrine precursor cellsfor about every 1 immature pancreatic islet hormone-expressing celland/or mature pancreatic islet hormone-expressing cell, at least about100,000 endocrine precursor cells for about every 1 immature pancreaticislet hormone-expressing cell and/or mature pancreatic islethormone-expressing cell and at least about 1,000,000 endocrine precursorcells for about every 1 immature pancreatic islet hormone-expressingcell and/or mature pancreatic islet pancreatic hormone-expressing cellare contemplated.

In some embodiments of the present invention, the PDX1-positive foregutendoderm cells from which endocrine precursor cells are produced arederived from human pluripotent cells, such as human pluripotent stemcells. In certain embodiments, the human pluripotent cells are derivedfrom a morula, the inner cell mass of an embryo or the gonadal ridges ofan embryo. In certain other embodiments, the human pluripotent cells arederived from the gonadal or germ tissues of a multicellular structurethat has developed past the embryonic stage.

Further embodiments of the present invention relate to compositions,such as cell cultures or cell populations, comprising human cells,including human endocrine precursor cells, wherein the expression of theNGN3 marker is greater than the expression of the AFP, SOX7, SOX1, ZIC1,NFM, MAFA, SYP, CHGA, INS, GCG, SST, GHRL, and/or PAX6 marker in atleast about 2% of the human cells. In other embodiments, the expressionof the NGN3 marker is greater than the expression of the AFP, SOX7,SOX1, ZIC1, NFM, MAFA, SYP, CHGA, INS, GCG, SST, GHRL, and/or PAX6marker in at least about 5% of the human cells, in at least about 10% ofthe human cells, in at least about 15% of the human cells, in at leastabout 20% of the human cells, in at least about 25% of the human cells,in at least about 30% of the human cells, in at least about 35% of thehuman cells, in at least about 40% of the human cells, in at least about45% of the human cells, in at least about 50% of the human cells, in atleast about 55% of the human cells, in at least about 60% of the humancells, in at least about 65% of the human cells, in at least about 70%of the human cells, in at least about 75% of the human cells, in atleast about 80% of the human cells, in at least about 85% of the humancells, in at least about 90% of the human cells, in at least about 95%of the human cells or in at least about 98% of the human cells. In someembodiments, the percentage of human cells in the cell cultures orpopulations, wherein the expression of NGN3 is greater than theexpression of the AFP, SOX7, SOX1, ZIC1, NFM, MAFA, SYP, CHGA, INS, GCG,SST, GHRL, and/or PAX6 marker, is calculated without regard to feedercells.

It will be appreciated that some embodiments of the present inventionrelate to compositions, such as cell cultures or cell populations,comprising human endocrine precursor cells, wherein the expression ofNKX2.2 and/or PAX4 is greater than the expression of the AFP, SOX7,SOX1, ZIC1, NFM, MAFA, SYP, CHGA, INS, GCG, SST, GHRL, and/or PAX6marker in from at least about 2% to greater than at least about 98% ofthe human cells. In some embodiments, the expression of NKX2.2 and/orPAX4 is greater than the expression of the AFP, SOX7, SOX1, ZIC1, NFM,MAFA, SYP, CHGA, INS, GCG, SST, GHRL, and/or PAX6 marker in at leastabout 5% of the human cells, in at least about 10% of the human cells,in at least about 15% of the human cells, in at least about 20% of thehuman cells, in at least about 25% of the human cells, in at least about30% of the human cells, in at least about 35% of the human cells, in atleast about 40% of the human cells, in at least about 45% of the humancells, in at least about 50% of the human cells, in at least about 55%of the human cells, in at least about 60% of the human cells, in atleast about 65% of the human cells, in at least about 70% of the humancells, in at least about 75% of the human cells, in at least about 80%of the human cells, in at least about 85% of the human cells, in atleast about 90% of the human cells, in at least about 95% of the humancells or in at least about 98% of the human cells. In some embodiments,the percentage of human cells in the cell cultures or populations,wherein the expression of NKX2.2 and/or PAX4 is greater than theexpression of the AFP, SOX7, SOX1, ZIC1, NFM, MAFA, SYP, CHGA, INS, GCG,SST, GHRL, and/or PAX6 marker, is calculated without regard to feedercells.

Additional embodiments of the present invention relate to compositions,such as cell cultures or cell populations, comprising mammalian cellsdifferentiated from definitive endoderm in vitro, such as human cellsdifferentiated from definitive endoderm in vitro, wherein the expressionof the NGN3, NKX2.2 and/or PAX4 marker is greater than the expression ofthe AFP, SOX7, SOX1, ZIC1, NFM, MAFA, SYP, CHGA, INS, GCG, SST, GHRL,and/or PAX6 marker in at least about 2% of the cells differentiated fromdefinitive endoderm in vitro. In other embodiments, the expression ofthe NGN3, NKX2.2 and/or PAX4 marker is greater than the expression ofthe AFP, SOX7, SOX1, ZIC1, NFM, MAFA, SYP, CHGA, INS, GCG, SST, GHRL,and/or PAX6 marker in at least about 5% of the cells differentiated fromdefinitive endoderm in vitro, in at least about 10% of the cellsdifferentiated from definitive endoderm in vitro, in at least about 15%of the cells differentiated from definitive endoderm in vitro, in atleast about 20% of the cells differentiated from definitive endoderm invitro, in at least about 25% of the cells differentiated from definitiveendoderm in vitro, in at least about 30% of the cells differentiatedfrom definitive endoderm in vitro, in at least about 35% of the cellsdifferentiated from definitive endoderm in vitro, in at least about 40%of the cells differentiated from definitive endoderm in vitro, in atleast about 45% of the cells differentiated from definitive endoderm invitro, in at least about 50% of the cells differentiated from definitiveendoderm in vitro, in at least about 55% of the cells differentiatedfrom definitive endoderm in vitro, in at least about 60% of the cellsdifferentiated from definitive endoderm in vitro, in at least about 65%of the cells differentiated from definitive endoderm in vitro, in atleast about 70% of the cells differentiated from definitive endoderm invitro, in at least about 75% of the cells differentiated from definitiveendoderm in vitro, in at least about 80% of the cells differentiatedfrom definitive endoderm in vitro, in at least about 85% of the cellsdifferentiated from definitive endoderm in vitro, in at least about 90%of the cells differentiated from definitive endoderm in vitro, in atleast about 95% of the cells differentiated from definitive endoderm invitro or in at least about 98% of the cells differentiated fromdefinitive endoderm in vitro.

In preferred embodiments of the present invention, cell cultures and/orcell populations of endocrine precursor cells comprise human endocrineprecursor cells that are non-recombinant cells. In such embodiments, thecell cultures and/or cell populations are devoid of or substantiallyfree of recombinant human endocrine precursor cells.

In some embodiments of the present invention, cell cultures and/or cellpopulations comprising endocrine precursor cells also include a mediumwhich comprises a gamma secretase inhibitor. In a preferred embodiment,the gamma secretase inhibitor isN—[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester(DAPT) In some preferred embodiments, the DAPT concentration is at leastabout 1 μM. In more preferred embodiments, the DAPT concentration is atleast about 3 μM. In some embodiments, the medium also comprises afactor selected from retinoic acid (RA) and exendin 4 (Ex4). In someembodiments, the medium is CMRL.

Using the processes described herein, compositions comprising endocrineprecursor cells substantially free of other cell types can be produced.In some embodiments of the present invention, the endocrine precursorcell populations or cell cultures produced by the methods describedherein are substantially free of cells that significantly express theAFP, SOX7, SOX1, ZIC1 and/or NFM markers. In some embodiments, theendocrine precursor cell populations of cell cultures produced by themethods described herein are substantially free of cells thatsignificantly express the AFP, SOX7, SOX1, ZIC1, NFM, MAFA, SYP, CHGA,INS, GCG, SST, GHRL, and/or PAX6 markers.

In one embodiment of the present invention, a description of a endocrineprecursor cell based on the expression of markers is, NGN3 high, NKX2.2high, PAX4 high, AFP low, SOX7 low, SOX1 low, ZIC1 low NFM low, MAFAlow; SYP low; CHGA low; INS low, GCG low, SST low, GHRL low and/or PAX6low.

Screening Pancreatic Endocrine Precursor Cells

Certain screening methods described herein relate to methods foridentifying at least one differentiation factor that is capable ofpromoting the differentiation of endocrine precursor cells.

In some embodiments of these differentiation screening methods, cellpopulations comprising endocrine precursor cells, such as humanendocrine precursor cells, are obtained. The cell population is thenprovided with a candidate differentiation factor. At a first time point,which is prior to or at approximately the same time as providing thecandidate differentiation factor, expression of a marker is determined.Alternatively, expression of the marker can be determined afterproviding the candidate differentiation factor. At a second time point,which is subsequent to the first time point and subsequent to the stepof providing the candidate differentiation factor to the cellpopulation, expression of the same marker is again determined. Whetherthe candidate differentiation factor is capable of promoting thedifferentiation of the endocrine precursor cells is determined bycomparing expression of the marker at the first time point with theexpression of the marker at the second time point. If expression of themarker at the second time point is increased or decreased as compared toexpression of the marker at the first time point, then the candidatedifferentiation factor is capable of promoting the differentiation ofendocrine precursor cells.

Some embodiments of the screening methods described herein utilize cellpopulations or cell cultures which comprise human endocrine precursorcells. For example, the cell population can be a substantially purifiedpopulation of endocrine precursor cells. Alternatively, the cellpopulation can be an enriched population of human endocrine precursorcells, wherein at least about 90%, at least about 91%, at least about92%, at least about 93%, at least about 94%, at least about 95%, atleast about 96%, at least about 97% or greater than at least about 97%of the human cells in the cell population are human endocrine precursorcells. In other embodiments described herein, the cell populationcomprises human cells wherein at least about 10%, at least about 15%, atleast about 20%, at least about 25%, at least about 30%, at least about35%, at least about 40%, at least about 45%, at least about 50%, atleast about 55%, at least about 60%, at least about 65%, at least about70%, at least about 75%, at least about 80%, at least about 85% orgreater than at least about 85% of the human cells are human endocrineprecursor cells. In some embodiments, the cell population includesnon-human cells such as non-human feeder cells. In other embodiments,the cell population includes human feeder cells. In such embodiments, atleast about 10%, at least about 15%, at least about 20%, at least about25%, at least about 30%, at least about 35%, at least about 40%, atleast about 45%, at least about 50%, at least about 55%, at least about60%, at least about 65%, at least about 70%, at least about 75%, atleast about 80%, at least about 85%, at least about 90%, at least about95% or greater than at least about 95% of the human cells, other thansaid feeder cells, are human endocrine precursor cells.

In embodiments of the screening methods described herein, the cellpopulation is contacted or otherwise provided with a candidate (test)differentiation factor. The candidate differentiation factor cancomprise any molecule that may have the potential to promote thedifferentiation of human endocrine precursor cells. In some embodimentsdescribed herein, the candidate differentiation factor comprises amolecule that is known to be a differentiation factor for one or moretypes of cells. In alternate embodiments, the candidate differentiationfactor comprises a molecule that in not known to promote celldifferentiation. In preferred embodiments, the candidate differentiationfactor comprises a molecule that is not known to promote thedifferentiation of human endocrine precursor cells.

In some embodiments of the screening methods described herein, thecandidate differentiation factor comprises a small molecule. Inpreferred embodiments, a small molecule is a molecule having a molecularmass of about 10,000 amu or less.

In other embodiments described herein, the candidate differentiationfactor comprises a polypeptide. The polypeptide can be any polypeptideincluding, but not limited to, a glycoprotein, a lipoprotein, anextracellular matrix protein, a cytokine, a chemokine, a peptidehormone, an interleukin or a growth factor. Preferred polypeptidesinclude growth factors.

In some embodiments of the screening methods described herein, thecandidate differentiation factors comprise one or more growth factorsselected from the group consisting of Amphiregulin, B-lymphocytestimulator, IL-16, Thymopoietin, TRAIL/Apo-2, Pre B cell colonyenhancing factor, Endothelial differentiation-related factor 1 (EDF1),Endothelial monocyte activating polypeptide II, Macrophage migrationinhibitory factor (MIF), Natural killer cell enhancing factor (NKEFA),Bone morphogenetic protein 2, Bone morphogenetic protein 8 (osteogeneicprotein 2), Bone morphogenic protein 6, Bone morphogenic protein 7,Connective tissue growth factor (CTGF), CGI-149 protein (neuroendocrinedifferentiation factor), Cytokine A3 (macrophage inflammatory protein1-alpha), Gliablastoma cell differentiation-related protein (GBDR1),Hepatoma-derived growth factor, Neuromedin U-25 precursor, Vascularendothelial growth factor (VEGF), Vascular endothelial growth factor B(VEGF-B), T-cell specific RANTES precursor, thymic dendriticcell-derived factor 1, Transferrin, Interleukin-1 (IL 1), Interleukin-2(IL 2), Interleukin-3 (IL 3), Interleukin-4 (IL 4), Interleukin-5 (IL5), Interleukin-6 (IL 6), Interleukin-7 (IL 7), Interleukin-8 (IL 8),Interleukin-9 (IL 9), Interleukin-10 (IL 10), Interleukin-11 (IL 11),Interleukin-12 (IL 12), Interleukin-13 (IL 13), Granulocyte-colonystimulating factor (G-CSF), Granulocyte macrophage colony stimulatingfactor (GM-CSF), Macrophage colony stimulating factor (M-CSF),Erythropoietin, Thrombopoietin, Vitamin D₃, Epidermal growth factor(EGF), Brain-derived neurotrophic factor, Leukemia inhibitory factor,Thyroid hormone, Basic fibroblast growth factor (bFGF), aFGF, FGF-4,FGF-6, FGF-7/Keratinocyte growth factor (KGF), Platelet-derived growthfactor (PDGF), Platelet-derived growth factor-BB, beta nerve growthfactor, activin A, Transforming growth factor beta 1 (TGF-β1),Interferon-α, Interferon-β, Interferon-γ, Tumor necrosis factor-α, Tumornecrosis factor-β, Burst promoting activity (BPA), Erythroid promotingactivity (EPA), PGE₂, insulin growth factor-1 (IGF-1), IGF-II,Neutrophin growth factor (NGF), Neutrophin-3, Neutrophin 4/5, Ciliaryneurotrophic factor, Glial-derived nexin, Dexamethasone,β-mercaptoethanol, Retinoic acid, Butylated hydroxyanisole,5-azacytidine, Amphotericin B, Ascorbic acid, Ascrorbate,isobutylxanthine, indomethacin, β-glycerolphosphate, nicotinamide, DMSO,Thiazolidinediones, TWS119, oxytocin, vasopressin,melanocyte-stimulating hormone, corticortropin, lipotropin, thyrotropin,growth hormone, prolactin, luteinizing hormone, human chorionicgonadotropin, follicle stimulating hormone, corticotropin-releasingfactor, gonadotropin-releasing factor, prolactin-releasing factor,prolactin-inhibiting factor, growth-hormone releasing factor,somatostatin, thyrotropin-releasing factor, calcitonin gene-relatedpeptide, parathyroid hormone, glucagon-like peptide 1, glucose-dependentinsulinotropic polypeptide, gastrin, secretin, cholecystokinin, motilin,vasoactive intestinal peptide, substance P, pancreatic polypeptide,peptide tyrosine tyrosine, neuropeptide tyrosine, insulin, glucagon,placental lactogen, relaxin, angiotensin II, calctriol, atrialnatriuretic peptide, and melatonin. thyroxine, triiodothyronine,calcitonin, estradiol, estrone, progesterone, testosterone, cortisol,corticosterone, aldosterone, epinephrine, norepinepherine, androstiene,calcitriol, collagen, Dexamethasone, β-mercaptoethanol, Retinoic acid,Butylated hydroxyanisole, 5-azacytidine, Amphotericin B, Ascorbic acid,Ascrorbate, isobutylxanthine, indomethacin, β-glycerolphosphate,nicotinamide, DMSO, Thiazolidinediones, and TWS119.

In some embodiments of the screening methods described herein, thecandidate differentiation factor is provided to the cell population inone or more concentrations. In some embodiments, the candidatedifferentiation factor is provided to the cell population so that theconcentration of the candidate differentiation factor in the mediumsurrounding the cells ranges from about 0.1 ng/ml to about 10 mg/ml. Insome embodiments, the concentration of the candidate differentiationfactor in the medium surrounding the cells ranges from about 1 ng/ml toabout 1 mg/ml. In other embodiments, the concentration of the candidatedifferentiation factor in the medium surrounding the cells ranges fromabout 10 ng/ml to about 100 μg/ml. In still other embodiments, theconcentration of the candidate differentiation factor in the mediumsurrounding the cells ranges from about 100 ng/ml to about 10 μg/ml. Inpreferred embodiments, the concentration of the candidatedifferentiation factor in the medium surrounding the cells is about 5ng/ml, about 25 ng/ml, about 50 ng/ml, about 75 ng/ml, about 100 ng/ml,about 125 ng/ml, about 150 ng/ml, about 175 ng/ml, about 200 ng/ml,about 225 ng/ml, about 250 ng/ml, about 275 ng/ml, about 300 ng/ml,about 325 ng/ml, about 350 ng/ml, about 375 ng/ml, about 400 ng/ml,about 425 ng/ml, about 450 ng/ml, about 475 ng/ml, about 500 ng/ml,about 525 ng/ml, about 550 ng/ml, about 575 ng/ml, about 600 ng/ml,about 625 ng/ml, about 650 ng/ml, about 675 ng/ml, about 700 ng/ml,about 725 ng/ml, about 750 ng/ml, about 775 ng/ml, about 800 ng/ml,about 825 ng/ml, about 850 ng/ml, about 875 ng/ml, about 900 ng/ml,about 925 ng/ml, about 950 ng/ml, about 975 ng/ml, about 1 μg/ml, about2 μg/ml, about 3 μg/ml, about 4 μg/ml, about 5 μg/ml, about 6 μg/ml,about 7 μg/ml, about 8 μg/ml, about 9 μg/ml, about 10 μg/ml, about 11μg/ml, about 12 μg/ml, about 13 μg/ml, about 14 μg/ml, about 15 μg/ml,about 16 μg/ml, about 17 μg/ml, about 18 μg/ml, about 19 μg/ml, about 20μg/ml, about 25 μg/ml, about 50 μg/ml, about 75 μg/ml, about 100 μg/ml,about 125 μg/ml, about 150 μg/ml, about 175 μg/ml, about 200 μg/ml,about 250 μg/ml, about 300 μg/ml, about 350 μg/ml, about 400 μg/ml,about 450 μg/ml, about 500 μg/ml, about 550 μg/ml, about 600 μg/ml,about 650 μg/ml, about 700 μg/ml, about 750 μg/ml, about 800 μg/ml,about 850 μg/ml, about 900 μg/ml, about 950 μg/ml, about 1000 μg/ml orgreater than about 1000 μg/ml.

In some embodiments, steps of the screening methods described hereincomprise determining expression of at least one marker at a first timepoint and a second time point. In some of these embodiments, the firsttime point can be prior to or at approximately the same time asproviding the cell population with the candidate differentiation factor.Alternatively, in some embodiments, the first time point is subsequentto providing the cell population with the candidate differentiationfactor. In some embodiments, expression of a plurality of markers isdetermined at a first time point.

Some preferred markers for use in the above embodiments include one ormore markers selected from the group consisting of NGN3, NKX2.2 andPAX4.

In addition to determining expression of at least one marker at a firsttime point, some embodiments of the screening methods described hereincontemplate determining expression of at least one marker at a secondtime point, which is subsequent to the first time point and which issubsequent to providing the cell population with the candidatedifferentiation factor. In such embodiments, expression of the samemarker is determined at both the first and second time points. In someembodiments, expression of a plurality of markers is determined at boththe first and second time points. In such embodiments, expression of thesame plurality of markers is determined at both the first and secondtime points. In some embodiments, marker expression is determined at aplurality of time points, each of which is subsequent to the first timepoint, and each of which is subsequent to providing the cell populationwith the candidate differentiation factor. In certain embodiments,marker expression is determined by Q-PCR. In other embodiments, markerexpression is determined by immunocytochemistry.

In certain embodiments of the screening methods described herein, themarker having its expression determined at the first and second timepoints is a marker that is associated with the differentiation ofendocrine precursor cells to cells which are the precursors ofterminally differentiated cells which make up pancreatic islet tissues.Such cells can include immature pancreatic islet hormone-expressingcells. In some embodiments, the marker is indicative of endocrineprecursor cells. In preferred embodiments, the marker is NGN3, NKX2.2,NKX6.1, PAX4, PDX1, insulin, ghrelin and/or glucagon.

In some embodiments of the screening methods described herein,sufficient time is allowed to pass between providing the cell populationwith the candidate differentiation factor and determining markerexpression at the second time point. Sufficient time between providingthe cell population with the candidate differentiation factor anddetermining expression of the marker at the second time point can be aslittle as from about 1 hour to as much as about 10 days. In someembodiments, the expression of at least one marker is determinedmultiple times subsequent to providing the cell population with thecandidate differentiation factor. In some embodiments, sufficient timeis at least about 1 hour, at least about 6 hours, at least about 12hours, at least about 18 hours, at least about 24 hours, at least about30 hours, at least about 36 hours, at least about 42 hours, at leastabout 48 hours, at least about 54 hours, at least about 60 hours, atleast about 66 hours, at least about 72 hours, at least about 78 hours,at least about 84 hours, at least about 90 hours, at least about 96hours, at least about 102 hours, at least about 108 hours, at leastabout 114 hours, at least about 120 hours, at least about 126 hours, atleast about 132 hours, at least about 138 hours, at least about 144hours, at least about 150 hours, at least about 156 hours, at leastabout 162 hours, at least about 168 hours, at least about 174 hours, atleast about 180 hours, at least about 186 hours, at least about 192hours, at least about 198 hours, at least about 204 hours, at leastabout 210 hours, at least about 216 hours, at least about 222 hours, atleast about 228 hours, at least about 234 hours, at least about 240hours, at least about 246 hours, at least about 252 hours, at leastabout 258 hours, at least about 264 hours, or at least about 270 hours.

In some embodiments of the methods described herein, it is furtherdetermined whether the expression of the marker at the second time pointhas increased or decreased as compared to the expression of this markerat the first time point. An increase or decrease in the expression ofthe at least one marker indicates that the candidate differentiationfactor is capable of promoting the differentiation of the endocrineprecursor cells. Similarly, if expression of a plurality of markers isdetermined, it is further determined whether the expression of theplurality of markers at the second time point has increased or decreasedas compared to the expression of this plurality of markers at the firsttime point. An increase or decrease in marker expression can bedetermined by measuring or otherwise evaluating the amount, level oractivity of the marker in the cell population at the first and secondtime points. Such determination can be relative to other markers, forexample housekeeping gene expression, or absolute. In certainembodiments, wherein marker expression is increased at the second timepoint as compared with the first time point, the amount of increase isat least about 2-fold, at least about 5-fold, at least about 10-fold, atleast about 20-fold, at least about 30-fold, at least about 40-fold, atleast about 50-fold, at least about 60-fold, at least about 70-fold, atleast about 80-fold, at least about 90-fold, at least about 100-fold ormore than at least about 100-fold. In some embodiments, the amount ofincrease is less than 2-fold. In embodiments where marker expression isdecreased at the second time point as compared with the first timepoint, the amount of decrease is at least about 2-fold, at least about5-fold, at least about 10-fold, at least about 20-fold, at least about30-fold, at least about 40-fold, at least about 50-fold, at least about60-fold, at least about 70-fold, at least about 80-fold, at least about90-fold, at least about 100-fold or more than at least about 100-fold.In some embodiments, the amount of decrease is less than 2-fold.

Production of Immature Pancreatic Islet Hormone-Expressing Cells

Embodiments of the present invention relate to methods of producingimmature pancreatic islet hormone-expressing cells starting from hESCs.As described above, immature pancreatic islet hormone-expressing cellscan be produced by first differentiating hESCs to produce definitiveendoderm cells, differentiating the definitive endoderm cells to produceforegut endoderm cells, differentiating foregut endoderm to producePDX1-positive foregut endoderm cells and then further differentiatingthe PDX1-positive foregut endoderm cells to produce endocrine precursorcells. In some embodiments, the process is continued by allowing theendocrine precursor cells to further differentiate to immaturepancreatic islet hormone-expressing cells.

In some embodiments of the present invention, differentiation fromendocrine precursor cells to immature pancreatic islethormone-expressing cells proceeds by continuing the incubation of aculture of endocrine precursor cells with a gamma secretase inhibitorfor a sufficient time that the cells stop substantially expressing NGN3,and start expressing PAX6, and to permit the cells to become competentto express at least one pancreatic islet cell hormone. In someembodiments, the gamma secretase inhibitor is removed about 1 day, about2 days, about 3 days, about 4 days, about 5 days, about 6 days, about 7days, about 8 days, about 9 days, about 10 days or more than about 10days after the induction of endocrine precursor cells. In a preferredembodiment, the gamma secretase inhibitor isN—[N-(3,5-Diflurophenacetyl-L-alanyl)]-S-phenylglycine t-Butyl Ester(DAPT).

Certain processes for the production of immature pancreatic islethormone-expressing cells disclosed herein are mediated by providing acell culture or cell population comprising human endocrine precursorcells with one or more factors selected from the group consisting ofnicotinamide, exendin 4, hepatocyte growth factor (HGF), insulin-likegrowth factor-1 (IGF1). In some embodiments, all four of theabove-described factors are provided together. In some embodiments, oneor more of the above-described factors are provided to the cell cultureprior to the differentiation of endocrine precursor cells and remainpresent in the cell culture during the differentiation of at least aportion of the cells in the cell culture to endocrine precursor cells.In other embodiments, one or more of the above-described factors areprovided to the cell culture at or about the time of differentiation ofa substantial portion of the cells to endocrine precursor cells andremain present in the cell culture until at least a substantial portionof the cells have differentiated into immature pancreatic islethormone-expressing cells. In some embodiments of the present invention,one or more of the above-described factors are provided at the start ofthe differentiation process, for example, at the hESC stage, and remainin the cell culture throughout the differentiation to immaturepancreatic islet hormone-expressing cells.

In some processes for the production of immature pancreatic islethormone-expressing cells disclosed herein, nicotinamide,nicotinamide-adenine dinucleotide (NAD), or nicotinic acid is providedto the cells so that it is present in the cell culture or cellpopulation at concentrations sufficient to promote differentiation of atleast a portion of the endocrine precursor cells to immature pancreaticislet hormone-expressing cells. In some embodiments, nicotinamide ispresent in the cell culture or cell population at a concentration of atleast about 0.1 mM, at least about 0.5 mM, at least about 1 mM, at leastabout 2 mM, at least about 3 mM, at least about 4 mM, at least about 5mM, at least about 6 mM, at least about 7 mM, at least about 8 mM, atleast about 9 mM, at least about 10 mM, at least about 11 mM, at leastabout 12 mM, at least about 13 mM, at least about 14 mM, at least about15 mM, at least about 16 mM, at least about 17 mM, at least about 18 mM,at least about 19 mM, at least about 20 mM, at least about 25 mM, atleast about 30 mM, at least about 35 mM, at least about 40 mM, at leastabout 45 mM, at least about 50 mM, at least about 55 mM, at least about60 mM, at least about 65 mM, at least about 70 mM, at least about 75 mM,at least about 80 mM, at least about 85 mM, at least about 90 mM, atleast about 95 mM, at least about 100 mM, at least about 250 mM, atleast about 500 mM or at least about 1000 mM.

In other processes for the production of immature pancreatic islethormone-expressing cells disclosed herein, exendin 4 is provided to thecells so that it is present in the cell culture or cell population atconcentrations sufficient to promote differentiation of at least aportion of the endocrine precursor cells to immature pancreatic islethormone-expressing cells. In some embodiments, exendin 4 is present inthe cell culture or cell population at a concentration of at least about1 ng/ml at least about 5 ng/ml, at least about 10 ng/ml, at least about15 ng/ml, at least about 20 ng/ml, at least about 25 ng/ml, at leastabout 30 ng/ml, at least about 35 ng/ml, at least about 40 ng/ml, atleast about 45 ng/ml, at least about 50 ng/ml, at least about 55 ng/ml,at least about 60 ng/ml, at least about 65 ng/ml, at least about 70ng/ml, at least about 75 ng/ml, at least about 80 ng/ml, at least about85 ng/ml, at least about 90 ng/ml, at least about 95 ng/ml, at leastabout 100 ng/ml, at least about 110 ng/ml, at least about 120 ng/ml, atleast about 130 ng/ml, at least about 140 ng/ml, at least about 150ng/ml, at least about 160 ng/ml, at least about 170 ng/ml, at leastabout 180 ng/ml, at least about 190 ng/ml, at least about 200 ng/ml, atleast about 250 ng/ml, at least about 300 ng/ml, at least about 350ng/ml, at least about 400 ng/ml, at least about 450 ng/ml, at leastabout 500 ng/ml, at least about 750 ng/ml, or at least about 1000 ng/ml.

In still other processes for the production of immature pancreatic islethormone-expressing cells disclosed herein, HGF is provided to the cellsso that it is present in the cell culture or cell population atconcentrations sufficient to promote differentiation of at least aportion of the endocrine precursor cells to immature pancreatic islethormone-expressing cells. In some embodiments, HGF is present in thecell culture or cell population at a concentration of at least about 1ng/ml at least about 5 ng/ml, at least about 10 ng/ml, at least about 15ng/ml, at least about 20 ng/ml, at least about 25 ng/ml, at least about30 ng/ml, at least about 35 ng/ml, at least about 40 ng/ml, at leastabout 45 ng/ml, at least about 50 ng/ml, at least about 55 ng/ml, atleast about 60 ng/ml, at least about 65 ng/ml, at least about 70 ng/ml,at least about 75 ng/ml, at least about 80 ng/ml, at least about 85ng/ml, at least about 90 ng/ml, at least about 95 ng/ml, at least about100 ng/ml, at least about 110 ng/ml, at least about 120 ng/ml, at leastabout 130 ng/ml, at least about 140 ng/ml, at least about 150 ng/ml, atleast about 160 ng/ml, at least about 170 ng/ml, at least about 180ng/ml, at least about 190 ng/ml, at least about 200 ng/ml, at leastabout 250 ng/ml, at least about 300 ng/ml, at least about 350 ng/ml, atleast about 400 ng/ml, at least about 450 ng/ml, at least about 500ng/ml, at least about 750 ng/ml, or at least about 1000 ng/ml.

In yet other processes for the production of immature pancreatic islethormone-expressing cells disclosed herein, IGF1 is provided to the cellsso that it is present in the cell culture or cell population atconcentrations sufficient to promote differentiation of at least aportion of the endocrine precursor cells to immature pancreatic islethormone-expressing cells. In some embodiments, IGF1 is present in thecell culture or cell population at a concentration of at least about 1ng/ml at least about 5 ng/ml, at least about 10 ng/ml, at least about 15ng/ml, at least about 20 ng/ml, at least about 25 ng/ml, at least about30 ng/ml, at least about 35 ng/ml, at least about 40 ng/ml, at leastabout 45 ng/ml, at least about 50 ng/ml, at least about 55 ng/ml, atleast about 60 ng/ml, at least about 65 ng/ml, at least about 70 ng/ml,at least about 75 ng/ml, at least about 80 ng/ml, at least about 85ng/ml, at least about 90 ng/ml, at least about 95 ng/ml, at least about100 ng/ml, at least about 110 ng/ml, at least about 120 ng/ml, at leastabout 130 ng/ml, at least about 140 ng/ml, at least about 150 ng/ml, atleast about 160 ng/ml, at least about 170 ng/ml, at least about 180ng/ml, at least about 190 ng/ml, at least about 200 ng/ml, at leastabout 250 ng/ml, at least about 300 ng/ml, at least about 350 ng/ml, atleast about 400 ng/ml, at least about 450 ng/ml, at least about 500ng/ml, at least about 750 ng/ml, or at least about 1000 ng/ml.

In certain embodiments of the processes for producing immaturepancreatic islet hormone-expressing cells as described herein, one ormore of nicotinamide, exendin 4, HGF and IGF1 are provided after one ormore previously provided differentiation factors have been removed fromthe cell cultures. In other embodiments, one or more of nicotinamide,exendin 4, HGF and IGF1 are provided to cell culture or cell populationcomprising one or more differentiation factors that were previouslyprovided or provided at about the same time as one or more ofnicotinamide, exendin 4, HGF and IGF1. In preferred embodiments,differentiation factors that were previously provided or provided atabout the same time as one or more of nicotinamide, exendin 4, HGF andIGF1 include, but are not limited to, DAPT, FGF-10, KAAD-cyclopamine,activin A, activin B, BMP4 and/or RA.

In one process for the production of immature pancreatic islethormone-expressing cells from endocrine precursor cells, a cell cultureor a cell population of endocrine precursor cells is provided with 10 mMnicotinamide, 40 ng/ml exendin 4, 25 ng/ml HGF and 50 ng/ml IGF1. In apreferred process, the cells are differentiated in Dulbecco's ModifiedEagle's Medium (DMEM).

In certain processes for producing immature pancreatic islethormone-expressing cells as described herein, one or more of theabove-mentioned differentiation factors are removed from the cellculture or cell population subsequent to their addition. For example,nicotinamide can be removed within about one day, about two days, aboutthree days, about four days, about five days, about six days, aboutseven days, about eight days, about nine days or about ten days afterthe addition. In some embodiments, the differentiation factors are notremoved from the cell culture.

Cultures of immature pancreatic islet hormone-expressing cells can beproduced in medium containing reduced serum or no serum. Under certainculture conditions, serum concentrations can range from about 0.05% v/vto about 20% v/v. For example, in some differentiation processes, theserum concentration of the medium can be less than about 0.05% (v/v),less than about 0.1% (v/v), less than about 0.2% (v/v), less than about0.3% (v/v), less than about 0.4% (v/v), less than about 0.5% (v/v), lessthan about 0.6% (v/v), less than about 0.7% (v/v), less than about 0.8%(v/v), less than about 0.9% (v/v), less than about 1% (v/v), less thanabout 2% (v/v), less than about 3% (v/v), less than about 4% (v/v), lessthan about 5% (v/v), less than about 6% (v/v), less than about 7% (v/v),less than about 8% (v/v), less than about 9% (v/v), less than about 10%(v/v), less than about 15% (v/v) or less than about 20% (v/v). In someprocesses, immature pancreatic islet hormone-expressing cells are grownwithout serum, without serum replacement and/or without any supplementcontaining insulin or insulin-like growth factor.

In still other processes, immature pancreatic islet hormone-expressingcells are grown in the presence of B27. In such processes, theconcentration of B27 supplement can range from about 0.1% (v/v) to about20% (v/v) or in concentrations greater than about 20% (v/v). In certainprocesses, the concentration of B27 in the medium is about 0.1% (v/v),about 0.2% (v/v), about 0.3% (v/v), about 0.4% (v/v), about 0.5% (v/v),about 0.6% (v/v), about 0.7% (v/v), about 0.8% (v/v), about 0.9% (v/v),about 1% (v/v), about 2% (v/v), about 3% (v/v), about 4% (v/v), about 5%(v/v), about 6% (v/v), about 7% (v/v), about 8% (v/v), about 9% (v/v),about 10% (v/v), about 15% (v/v) or about 20% (v/v). Alternatively, theconcentration of the added B27 supplement can be measured in terms ofmultiples of the strength of a commercially available B27 stocksolution. For example, B27 is available from Invitrogen (Carlsbad,Calif.) as a 50× stock solution. Addition of a sufficient amount of thisstock solution to a sufficient volume of growth medium produces a mediumsupplemented with the desired amount of B27. For example, the additionof 10 ml of 50×B27 stock solution to 90 ml of growth medium wouldproduce a growth medium supplemented with 5×B27. The concentration ofB27 supplement in the medium can be about 0.1×, about 0.2×, about 0.3×,about 0.4×, about 0.5×, about 0.6×, about 0.7×, about 0.8×, about 0.9×,about 1×, about 1.1×, about 1.2×, about 1.3×, about 1.4×, about 1.5×,about 1.6×, about 1.7×, about 1.8×, about 1.9×, about 2×, about 2.5×,about 3×, about 3.5×, about 4×, about 4.5×, about 5×, about 6×, about7×, about 8×, about 9×, about 10×, about 11×, about 12×, about 13×,about 14×, about 15×, about 16×, about 17×, about 18×, about 19×, about20× and greater than about 20×.

Monitoring the Production of Immature Pancreatic IsletHormone-Expressing Cells

The progression of endocrine precursor cells to immature pancreaticislet hormone-expressing cells can be monitored by determining theexpression of markers characteristic of immature islethormone-expressing cells, including genetic markers and phenotypicmarkers such as, the expression of islet hormones and the processing ofproinsulin into insulin and C peptide. In some processes, the expressionof certain markers is determined by detecting the presence or absence ofthe marker. Alternatively, the expression of certain markers can bedetermined by measuring the level at which the marker is present in thecells of the cell culture or cell population. In certain processes, theexpression of markers characteristic of immature pancreatic islethormone-expressing cells as well as the lack of significant expressionof markers characteristic of hESCs, definitive endoderm, foregutendoderm, PDX1-positive foregut endoderm, endocrine precursor,extraembryonic endoderm, mesoderm, ectoderm, mature pancreatic islethormone-expressing cells and/or other cell types is determined.

As described in connection with monitoring the production of other lessdifferentiated cell types of the definitive endoderm lineage,qualitative or semi-quantitative techniques, such as blot transfermethods and immunocytochemistry, can be used to measure markerexpression. Alternatively, marker expression can be accuratelyquantitated through the use of technique such as Q-PCR. Additionally, itwill be appreciated that at the polypeptide level, many of the markersof pancreatic islet hormone-expressing cells are secreted proteins. Assuch, techniques for measuring extracellular marker content, such asELISA, may be utilized.

As set forth in the Examples below, markers of immature pancreatic islethormone-expressing cells include, but are not limited to, MAFB, SYP,CHGA, NKX2.2, ISL1, PAX6, NEUROD, PDX1, HB9, GHRL, IAPP, INS, GCG, SST,PP, and/or connecting peptide (C-peptide). The immature pancreatic islethormone-expressing cells produced by the processes described hereinexpress one or more of the above-listed markers, thereby producing thecorresponding gene products. However, it will be appreciated thatimmature pancreatic islet hormone-expressing cells need not express allof the above-described markers. For example, pancreatic islethormone-expressing cells differentiated from hESCs do not co-express INSand GHRL.

Because pancreatic islet hormone-expressing cells do not substantiallyexpress the endocrine precursor cell markers NGN3 and PAX4, transitionof endocrine precursor cells to immature pancreatic islethormone-expressing cells can be validated by monitoring the decrease inexpression of NGN3 and PAX4 while monitoring the increase in expressionof one or more of MAFB, PAX6, GHRL IAPP, INS, GCG, NKX6.1, SST, PP,CHGA, SYP and/or C-peptide. In addition to monitoring the increaseand/or decrease in expression of one or more the above-describedmarkers, in some processes, the expression of genes indicative hESCs,definitive endoderm cells, foregut endoderm cells, PDX1-positive foregutendoderm cells and/or endocrine precursor cells is also monitored.

It will be appreciated that MAFB, PAX6, GHRL, IAPP, INS, GCG, NKX6.1,SST, PP, CHGA, SYP and/or C-peptide marker expression is induced over arange of different levels in immature pancreatic islethormone-expressing cells depending on the differentiation conditions. Assuch, in some embodiments described herein, the expression of MAFB,PAX6, GHRL, IAPP, INS, GCG, NKX6.1, SST, PP, CHGA, SYP, and/or C-peptidemarkers in pancreatic islet hormone-expressing cells or cell populationsis at least about 2-fold higher to at least about 10.000-fold higherthan the expression of MAFB, PAX6, GHRL, IAPP, INS, GCG, NKX6.1, SST,PP, CHGA, SYP and/or C-peptide markers in non-immature pancreatic islethormone-expressing cells or cell populations, for example pluripotentstem cells, definitive endoderm cells, foregut endoderm, PDX1-positiveforegut endoderm cells, endocrine precursor cells, extraembryonicendoderm cells, mesoderm cells, and/or ectoderm cells. In otherembodiments, the expression of the MAFB, PAX6, GHRL, IAPP, INS, GCG,NKX6.1, SST, PP, CHGA, SYP and/or C-peptide markers in immaturepancreatic islet hormone-expressing cells or cell populations is atleast about 4-fold higher, at least about 6-fold higher, at least about8-fold higher, at least about 10-fold higher, at least about 15-foldhigher, at least about 20-fold higher, at least about 40-fold higher, atleast about 80-fold higher, at least about 100-fold higher, at leastabout 150-fold higher, at least about 200-fold higher, at least about500-fold higher, at least about 750-fold higher, at least about1000-fold higher, at least about 2500-fold higher, at least about5000-fold higher, at least about 7500-fold higher or at least about10.000-fold higher than the expression of the MAFB, PAX6, GHRL, IAPP,INS, GCG, NKX2.2, SST, PP, CHGA, SYP and/or C-peptide markers innon-immature pancreatic islet hormone-expressing cells or cellpopulations, for example pluripotent stem cells, definitive endodermcells, foregut endoderm cells, PDX1-positive foregut endoderm cells,endocrine precursor cells, extraembryonic endoderm cells, mesoderm cellsand/or ectoderm cells. In some embodiments, the expression of the MAFB,PAX6, GHRL, IAPP, INS, GCG, NKX2.2, SST, PP, CHGA, SYP and/or C-peptidemarkers in immature pancreatic islet hormone-expressing cells or cellpopulations is infinitely higher than the expression of the MAFB, PAX6,GHRL, IAPP, INS, GCG, NKX2.2, SST, PP, CHGA, SYP and/or C-peptidemarkers in non-immature pancreatic islet hormone-expressing cells orcell populations, for example pluripotent stem cells, definitiveendoderm cells, foregut endoderm cells PDX1-positive foregut endodermcells, endocrine precursor cells, extraembryonic endoderm cells,mesoderm cells and/or ectoderm cells.

It will also be appreciated that NGN3 and/or PAX4 marker expressiondecreases over a range of different levels in immature pancreatic islethormone-expressing cells depending on the differentiation conditions. Assuch, in some embodiments described herein, the expression of NGN3and/or PAX4 markers in immature pancreatic islet hormone-expressingcells or cell populations is at least about 2-fold lower to at leastabout 10.000-fold lower than the expression of NGN3 and/or PAX4 markersin endocrine precursor cells. In other embodiments, the expression ofthe NGN3 and/or PAX4 markers in immature pancreatic islethormone-expressing cells or cell populations is at least about 4-foldlower, at least about 6-fold lower, at least about 8-fold lower, atleast about 10-fold lower, at least about 15-fold lower, at least about20-fold lower, at least about 40-fold lower, at least about 80-foldlower, at least about 100-fold lower, at least about 150-fold lower, atleast about 200-fold lower, at least about 500-fold lower, at leastabout 750-fold lower, at least about 1000-fold lower, at least about2500-fold lower, at least about 5000-fold lower, at least about7500-fold lower or at least about 10.000-fold lower than the expressionof the NGN3 and/or PAX4 markers in endocrine precursor cells. In someembodiments, the NGN3 and/or PAX4 markers are not substantiallyexpressed in immature pancreatic islet hormone-expressing cells or cellpopulations.

In some embodiments of the processes described herein, the amount ofhormone release from cells and/or cell populations can be determined.For example, the amount of insulin release, glucagon release,somatostatin release and/or ghrelin release can be monitored. In apreferred embodiment, the amount of insulin secreted in response toglucose (GSIS) is measured. In still other embodiments, secretedbreakdown or by-products produced by the immature pancreatic islethormone-expressing cells, such as c-peptide and islet amyloid protein,can be monitored.

It will be appreciated that methods of measuring the expression ofsecreted proteins are well known in the art. For example, an antibodyagainst one or more hormones produced by islet cells can be used inELISA assays.

In some embodiments of the present invention, insulin release byimmature pancreatic islet hormone-expressing cells is measured bymeasuring C-peptide release. C-peptide is a cleavage product that isproduced in equal molar amounts to insulin during the maturation ofpro-insulin. Measuring C-peptide is advantageous because its half lifeis longer than that of insulin. Methods of measuring C-peptide releaseare well known in the art, for example, ELISA using anti-C-peptidemonoclonal antibody (Linco Research, St. Louis, Mo.). In someembodiments of the present invention, immature pancreatic islethormone-expressing cells produced from hESCs secrete at least about 50pmol of C-peptide (insulin)/μg of cellular DNA, at least about 100 pmolof C-peptide (insulin)/μg of cellular DNA, at least about 150 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 200 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 250 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 300 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 350 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 400 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 450 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 500 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 550 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 600 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 650 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 700 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 750 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 800 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 850 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 900 pmol ofC-peptide (insulin)/μg of cellular DNA, at least about 950 pmol ofC-peptide (insulin)/μg of cellular DNA or at least about 1000 pmol ofC-peptide (insulin)/μg of cellular DNA. In preferred embodiments, theimmature pancreatic islet hormone-expressing cells are cells thatsecrete a single type of islet cell hormone (for example, the cellssecrete only insulin). In certain preferred embodiments, the insulin issecreted in response to glucose. In other embodiments, the immaturepancreatic islet hormone-expressing cells are cells that secrete insulinin addition to one or more islet cell hormones, for example,somatostatin, glucagon and/or ghrelin.

In some embodiments of the present invention, immature pancreatic islethormone-expressing cells process less than about 98% of the insulinproduced by said immature pancreatic islet hormone-expressing cells. Inother embodiments, the immature pancreatic islet hormone-expressingcells process less than about 97%, less than about 96%, less than about95%, less than about 94%, less than about 93%, less than about 92%, lessthan about 91%, less than about 90%, less than about 85%, less thanabout 80%, less than about 75%, less than about 70%, less than about65%, less than about 60%, less than about 55%, less than about 50%, lessthan about 45%, less than about 40%, less than about 35%, or less thanabout 30% of the insulin produced by said immature pancreatic islethormone-expressing cells.

In other embodiments of the present invention, immature pancreatic islethormone-expressing cells produced from hESCs secrete at least about 50pmol of glucagon/μg of cellular DNA, at least about 100 pmol ofglucagon/μg of cellular DNA, at least about 150 pmol of glucagon/μg ofcellular DNA, at least about 200 pmol of glucagon/μg of cellular DNA, atleast about 250 pmol of glucagon/μg of cellular DNA, at least about 300pmol of glucagon/μg of cellular DNA, at least about 350 pmol ofglucagon/μg of cellular DNA, at least about 400 pmol of glucagon/μg ofcellular DNA, at least about 450 pmol of glucagon/μg of cellular DNA, atleast about 500 pmol of glucagon/μg of cellular DNA, at least about 550pmol of glucagon/μg of cellular DNA, at least about 600 pmol ofglucagon/μg of cellular DNA, at least about 650 pmol of glucagon/μg ofcellular DNA, at least about 700 pmol of glucagon/μg of cellular DNA, atleast about 750 pmol of glucagon/μg of cellular DNA, at least about 800pmol of glucagon/μg of cellular DNA, at least about 850 pmol ofglucagon/μg of cellular DNA, at least about 900 pmol of glucagon/μg ofcellular DNA, at least about 950 pmol of glucagon/μg of cellular DNA orat least about 1000 pmol of glucagon/μg of cellular DNA. In preferredembodiments, the immature pancreatic islet hormone-expressing cells arecells that secrete a single type of islet cell hormone (for example, thecells secrete only glucagon). In other embodiments, the immaturepancreatic islet hormone-expressing cells are cells that secreteglucagon in addition to one or more islet cell hormones, for example,ghrelin, somatostatin and insulin.

In still other embodiments of the present invention, immature pancreaticislet hormone-expressing cells produced from hESCs secrete at leastabout 50 pmol of somatostatin/μg of cellular DNA, at least about 100pmol of somatostatin/μg of cellular DNA, at least about 150 pmol ofsomatostatin/μg of cellular DNA, at least about 200 pmol ofsomatostatin/μg of cellular DNA, at least about 250 pmol ofsomatostatin/μg of cellular DNA, at least about 300 pmol ofsomatostatin/μg of cellular DNA, at least about 350 pmol ofsomatostatin/μg of cellular DNA, at least about 400 pmol ofsomatostatin/μg of cellular DNA, at least about 450 pmol ofsomatostatin/μg of cellular DNA, at least about 500 pmol ofsomatostatin/μg of cellular DNA, at least about 550 pmol ofsomatostatin/μg of cellular DNA, at least about 600 pmol ofsomatostatin/μg of cellular DNA, at least about 650 pmol ofsomatostatin/μg of cellular DNA, at least about 700 pmol ofsomatostatin/μg of cellular DNA, at least about 750 pmol ofsomatostatin/μg of cellular DNA, at least about 800 pmol ofsomatostatin/μg of cellular DNA, at least about 850 pmol ofsomatostatin/μg of cellular DNA, at least about 900 pmol ofsomatostatin/μg of cellular DNA, at least about 950 pmol ofsomatostatin/μg of cellular DNA or at least about 1000 pmol ofsomatostatin/μg of cellular DNA. In preferred embodiments, the immaturepancreatic islet hormone-expressing cells are cells that secrete asingle type of islet cell hormone (for example, the cells secrete onlysomatostatin). In other embodiments, the immature pancreatic islethormone-expressing cells are cells that secrete somatostatin in additionto one or more islet cell hormones, for example, ghrelin, glucagon andinsulin.

In other embodiments of the present invention, immature pancreatic islethormone-expressing cells produced from hESCs secrete at least about 50pmol of ghrelin/μg of cellular DNA, at least about 100 pmol ofghrelin/μg of cellular DNA, at least about 150 pmol of ghrelin/μg ofcellular DNA, at least about 200 pmol of ghrelin/μg of cellular DNA, atleast about 250 pmol of ghrelin/μg of cellular DNA, at least about 300pmol of ghrelin/μg of cellular DNA, at least about 350 pmol ofghrelin/μg of cellular DNA, at least about 400 pmol of ghrelin/μg ofcellular DNA, at least about 450 pmol of ghrelin/μg of cellular DNA, atleast about 500 pmol of ghrelin/μg of cellular DNA, at least about 550pmol of ghrelin/μg of cellular DNA, at least about 600 pmol ofghrelin/μg of cellular DNA, at least about 650 pmol of ghrelin/μg ofcellular DNA, at least about 700 pmol of ghrelin/μg of cellular DNA, atleast about 750 pmol of ghrelin/μg of cellular DNA, at least about 800pmol of ghrelin/μg of cellular DNA, at least about 850 pmol ofghrelin/μg of cellular DNA, at least about 900 pmol of ghrelin/μg ofcellular DNA, at least about 950 pmol of ghrelin/μg of cellular DNA orat least about 1000 pmol of ghrelin/μg of cellular DNA. In preferredembodiments, the immature pancreatic islet hormone-expressing cells arecells that secrete a single type of islet cell hormone (for example, thecells secrete only ghrelin). In other embodiments, the immaturepancreatic islet hormone-expressing cells are cells that secrete ghrelinin addition to one or more islet cell hormones.

Enrichment Isolation and/or Purification of Immature Pancreatic IsletHormone-Expressing Cells

Immature pancreatic islet hormone-expressing cells produced by any ofthe above-described processes can be enriched, isolated and/or purifiedby using an affinity tag that is specific for such cells using themethods described in connection with the enrichment, isolation and/orpurification of endocrine precursor cells. Examples of affinity tagsspecific for immature pancreatic islet hormone-expressing cells areantibodies, ligands or other binding agents that are specific to amarker molecule, such as a polypeptide, that is present on the cellsurface of immature pancreatic islet hormone-expressing cells but whichis not substantially present on other cell types that would be found ina cell culture produced by the methods described herein. A preferredexample of an affinity tag for the enrichment, isolation and/orpurification of immature pancreatic islet hormone-expressing cells is anantibody against NCAM. Anti-NCAM antibodies are commercially available,for example from Abcam (Cambridge, Mass.). Another example of anaffinity tag for the enrichment, isolation and/or purification ofimmature pancreatic islet hormone-expressing is an antibody againstsynaptophysin (SYP). Anti-synaptophysin antibodies are commerciallyavailable from Dako (Glostrup, Denmark). In other processes, the NCAMligand NBP10, or any other NCAM ligand now known or discovered in thefuture can also be used to bind affinity tags. (Rohn, L., 2002). Suchmolecules include, but are not limited to, NBP10 fusions and NBP10mimetics.

Additional methods for obtaining enriched, isolated or purified immaturepancreatic islet hormone-expressing cell cultures or populations canalso be used. For example, in some embodiments, the reagent, such as anNCAM antibody, is incubated with a cell culture containing immaturepancreatic islet hormone-expressing cells, wherein the cell culture hasbeen treated to reduce intercellular and substrate adhesion. The cellsare then washed, centrifuged and resuspended. The cell suspension isthen incubated with a secondary antibody, such as an FITC-conjugatedantibody that is capable of binding to the primary antibody. The cellsare then washed, centrifuged and resuspended in buffer. The cellsuspension is then analyzed and sorted using a fluorescence activatedcell sorter (FACS). Antibody-bound, fluorescent cells are collectedseparately from non-bound, non-fluorescent, thereby resulting in theisolation of such cell types.

In preferred embodiments of the processes described herein, the isolatedcell compositions can be further purified by using an alternateaffinity-based method or by additional rounds of sorting using the sameor different markers that are specific for immature pancreatic islethormone-expressing cells. For example, in some embodiments, FACS sortingis used to first isolate NCAM-positive immature pancreatichormone-expressing cells from NCAM negative cells from cell populationscomprising immature pancreatic hormone-expressing cells. Those skilledin the art will appreciate that other conventional marker-based cellsorting methods can be used in the methods described herein, includingbut not limited to differential magnetic bead sorting, or panning.Sorting the NCAM positive cells again using FACS to isolate cells thatare NCAM positive enriches the cell population for immature pancreatichormone expressing cells that express markers characteristic of thiscell type, including SYP, CHGA, NKX2.2, ISL1, PAX6, NEUROD, PDX1, orHB9. In other embodiments, FACS sorting is used to separate cells bynegatively sorting for a marker that is present on most cells in thecell population other than the immature pancreatic islethormone-expressing cells. An example of such a negative sort is the useof CD133, which is a marker that is not substantially expressed on thesurface of immature pancreatic islet hormone-expressing cells in theNCAM positive cell population after the first round of enrichment butwhich is expressed on many other NCAM positive cells in this cellpopulation.

In some embodiments of the processes described herein, immaturepancreatic islet hormone-expressing cells are fluorescently labeledwithout the use of an antibody then isolated from non-labeled cells byusing a fluorescence activated cell sorter (FACS) methods similar tothose described for the enrichment, isolation and/or purification ofendocrine precursor cells. For example, in some embodiments, nucleicacids encoding GFP, YFP, luciferase biologically active fragmentsthereof can be introduced into a pluripotent cell downstream of thepromoter of a marker useful in the identification of immature pancreaticislet hormone-expressing cells such as those described above, forexample, SYP, CHGA, NKX2.2, ISL1, PAX6, NEUROD, PDX1, or HB9. Thereby,the expression GFP gene product or biologically active fragment thereofis under control of the immature pancreatic islet hormone-expressingcell marker. As described in connection with the enrichment, isolationand/or purification of endocrine precursor cells, fluorescently markedcells can be differentiated to immature pancreatic islethormone-expressing cells and separated from other cell types, therebyproducing an enriched or purified population of immature pancreaticislet hormone-expressing cells.

It will be appreciated that in addition to the procedures justdescribed, immature pancreatic islet hormone-expressing cells may alsobe isolated by other techniques for cell isolation. Additionally,immature pancreatic islet hormone-expressing cells may also be enrichedor isolated by methods of serial subculture in growth conditions whichpromote the selective survival or selective expansion of the immaturepancreatic islet hormone-expressing cells.

Using the methods described herein, enriched, isolated and/or purifiedpopulations of immature pancreatic islet hormone-expressing cells and ortissues can be produced in vitro from pluripotent cell cultures or cellpopulations, such as stem cell cultures or populations, which haveundergone sufficient differentiation to produce at least some immaturepancreatic islet hormone-expressing cells. In a preferred method, thecells are directed to differentiate primarily into immature pancreaticislet hormone-expressing cells. Some preferred enrichment, isolationand/or purification methods relate to the in vitro production ofimmature pancreatic islet hormone-expressing cells from human embryonicstem cells.

Using the methods described herein, cell populations or cell culturescan be enriched in immature pancreatic islet hormone-expressing cellcontent by at least about 2- to about 1000-fold as compared to untreatedor less specifically differentiated cell populations or cell cultures.In some embodiments, immature pancreatic islet hormone-expressing cellscan be enriched by at least about 5- to about 500-fold as compared tountreated or less specifically differentiated cell populations or cellcultures. In other embodiments, immature pancreatic islethormone-expressing cells can be enriched from at least about 10- toabout 200-fold as compared to untreated or less specificallydifferentiated cell populations or cell cultures. In still otherembodiments, immature pancreatic islet hormone-expressing cells can beenriched from at least about 20- to about 100-fold as compared tountreated or less specifically differentiated cell populations or cellcultures. In yet other embodiments, immature pancreatic islethormone-expressing cells can be enriched from at least about 40- toabout 80-fold as compared to untreated or less specificallydifferentiated cell populations or cell cultures. In certainembodiments, immature pancreatic islet hormone-expressing cells can beenriched from at least about 2- to about 20-fold as compared tountreated or less specifically differentiated cell populations or cellcultures.

Compositions Comprising Immature Pancreatic Islet Hormone-ExpressingCells

Some embodiments of the present invention relate to cell compositions,such as cell cultures or cell populations, comprising immaturepancreatic islet hormone-expressing cells, wherein the immaturepancreatic islet hormone-expressing cells are cells, which have beenderived from human pluripotent cells in vitro, which express one or morepancreatic hormones and which have at least some of the functions ofhuman pancreatic islet cells. In accordance with certain embodiments,the immature pancreatic islet hormone-expressing cells are mammaliancells, and in a preferred embodiment, such cells are human cells.

Other embodiments of the present invention relate to compositions, suchas cell cultures or cell populations, comprising immature pancreaticislet hormone-expressing cells and cells that are less specificallydifferentiated than immature pancreatic islet hormone-expressing cells.In such embodiments, cells that are less specifically differentiatedthan immature pancreatic islet hormone-expressing cells comprise lessthan about 90%, less than about 85%, less than about 80%, less thanabout 75%, less than about 70%, less than about 65%, less than about60%, less than about 55%, less than about 50%, less than about 45%, lessthan about 40%, less than about 35%, less than about 30%, less thanabout 25%, less than about 20%, less than about 15%, less than about12%, less than about 10%, less than about 8%, less than about 6%, lessthan about 5%, less than about 4%, less than about 3%, less than about2% or less than about 1% of the total cells in the culture.

Certain other embodiments of the present invention relate tocompositions, such as cell cultures or cell populations, comprisingimmature pancreatic islet hormone-expressing cells and cells of one ormore cell types selected from the group consisting of hESCs,pre-primitive streak cells, mesendoderm cells, definitive endodermcells, PDX1-negative foregut endoderm cells, PDX1-positive foregutendoderm cells (PDX1-positive pancreatic endoderm cells), endocrineprecursor cells and mesoderm cells. In some embodiments, hESCs compriseless than about 25%, less than about 20%, less than about 15%, less thanabout 10%, less than about 5%, less than about 4%, less than about 3%,less than about 2% or less than about 1% of the total cells in theculture. In certain embodiments, pre-primitive streak cells compriseless than about 25%, less than about 20%, less than about 15%, less thanabout 10%, less than about 5%, less than about 4%, less than about 3%,less than about 2% or less than about 1% of the total cells in theculture. In other embodiments, mesendoderm cells comprise less thanabout 25%, less than about 20%, less than about 15%, less than about10%, less than about 5%, less than about 4%, less than about 3%, lessthan about 2% or less than about 1% of the total cells in the culture.In still other embodiments, definitive endoderm cells comprise less thanabout 90%, less than about 85%, less than about 80%, less than about75%, less than about 70%, less than about 65%, less than about 60%, lessthan about 55%, less than about 50%, less than about 45%, less thanabout 40%, less than about 35%, less than about 30%, less than about25%, less than about 20%, less than about 15%, less than about 12%, lessthan about 10%, less than about 8%, less than about 6%, less than about5%, less than about 4%, less than about 3%, less than about 2% or lessthan about 1% of the total cells in the culture. In yet otherembodiments, PDX1-negative foregut endoderm cells comprise less thanabout 90%, less than about 85%, less than about 80%, less than about75%, less than about 70%, less than about 65%, less than about 60%, lessthan about 55%, less than about 50%, less than about 45%, less thanabout 40%, less than about 35%, less than about 30%, less than about25%, less than about 20%, less than about 15%, less than about 12%, lessthan about 10%, less than about 8%, less than about 6%, less than about5%, less than about 4%, less than about 3%, less than about 2% or lessthan about 1% of the total cells in the culture. In certain embodiments,PDX1-positive foregut endoderm cells comprise less than about 90%, lessthan about 85%, less than about 80%, less than about 75%, less thanabout 70%, less than about 65%, less than about 60%, less than about55%, less than about 50%, less than about 45%, less than about 40%, lessthan about 35%, less than about 30%, less than about 25%, less thanabout 20%, less than about 15%, less than about 12%, less than about10%, less than about 8%, less than about 6%, less than about 5%, lessthan about 4%, less than about 3%, less than about 2% or less than about1% of the total cells in the culture. In other embodiments, endocrineprecursor cells comprise less than about 90%, less than about 85%, lessthan about 80%, less than about 75%, less than about 70%, less thanabout 65%, less than about 60%, less than about 55%, less than about50%, less than about 45%, less than about 40%, less than about 35%, lessthan about 30%, less than about 25%, less than about 20%, less thanabout 15%, less than about 12%, less than about 10%, less than about 8%,less than about 6%, less than about 5%, less than about 4%, less thanabout 3%, less than about 2% or less than about 1% of the total cells inthe culture. In still other embodiments, mesoderm cells comprise lessthan about 90%, less than about 85%, less than about 80%, less thanabout 75%, less than about 70%, less than about 65%, less than about60%, less than about 55%, less than about 50%, less than about 45%, lessthan about 40%, less than about 35%, less than about 30%, less thanabout 25%, less than about 20%, less than about 15%, less than about12%, less than about 10%, less than about 8%, less than about 6%, lessthan about 5%, less than about 4%, less than about 3%, less than about2% or less than about 1% of the total cells in the culture.

Additional embodiments of the present invention relate to compositions,such as cell cultures or cell populations, produced by the processesdescribed herein and which comprise immature pancreatic islethormone-expressing cells as the majority cell type. In some embodiments,the processes described herein produce cell cultures and/or cellpopulations comprising at least about 99%, at least about 98%, at leastabout 97%, at least about 96%, at least about 95%, at least about 94%,at least about 93%, at least about 92%, at least about 91%, at leastabout 90%, at least about 89%, at least about 88%, at least about 87%,at least about 86%, at least about 85%, at least about 84%, at leastabout 83%, at least about 82%, at least about 81%, at least about 80%,at least about 79%, at least about 78%, at least about 77%, at leastabout 76%, at least about 75%, at least about 74%, at least about 73%,at least about 72%, at least about 71%, at least about 70%, at leastabout 69%, at least about 68%, at least about 67%, at least about 66%,at least about 65%, at least about 64%, at least about 63%, at leastabout 62%, at least about 61%, at least about 60%, at least about 59%,at least about 58%, at least about 57%, at least about 56%, at leastabout 55%, at least about 54%, at least about 53%, at least about 52%,at least about 51% or at least about 50% immature pancreatic islethormone-expressing cells. In preferred embodiments, the cells of thecell cultures or cell populations comprise human cells. In otherembodiments, the processes described herein produce cell cultures orcell populations comprising at least about 50%, at least about 45%, atleast about 40%, at least about 35%, at least about 30%, at least about25%, at least about 24%, at least about 23%, at least about 22%, atleast about 21%, at least about 20%, at least about 19%, at least about18%, at least about 17%, at least about 16%, at least about 15%, atleast about 14%, at least about 13%, at least about 12%, at least about11%, at least about 10%, at least about 9%, at least about 8%, at leastabout 7%, at least about 6%, at least about 5%, at least about 4%, atleast about 3%, at least about 2% or at least about 1% immaturepancreatic islet hormone-expressing cells. In preferred embodiments, thecells of the cell cultures or cell populations comprise human cells. Insome embodiments, the percentage of immature pancreatic islethormone-expressing cells in the cell cultures or populations iscalculated without regard to the feeder cells remaining in the culture.

Still other embodiments of the present invention relate to compositions,such as cell cultures or cell populations, comprising mixtures ofimmature pancreatic islet hormone-expressing cells and endocrineprecursor cells. For example, cell cultures or cell populationscomprising at least about 5 immature pancreatic islet hormone-expressingcells for about every 95 endocrine precursor cells can be produced. Inother embodiments, cell cultures or cell populations comprising at leastabout 95 immature pancreatic islet hormone-expressing cells for aboutevery 5 endocrine precursor cells can be produced. Additionally, cellcultures or cell populations comprising other ratios of immaturepancreatic islet hormone-expressing cells to endocrine precursor cellsare contemplated. For example, compositions comprising at least about 1immature pancreatic islet hormone-expressing cell for about every1,000,000 endocrine precursor cells, at least about 1 immaturepancreatic islet hormone-expressing cell for about every 100,000endocrine precursor cells, at least about 1 immature pancreatic islethormone-expressing cell for about every 10,000 endocrine precursorcells, at least about 1 immature pancreatic islet hormone-expressingcell for about every 1000 endocrine precursor cells, at least about 1immature pancreatic islet hormone-expressing cell for about every 500endocrine precursor cells, at least about 1 immature pancreatic islethormone-expressing cell for about every 100 endocrine precursor cells,at least about 1 immature pancreatic islet hormone-expressing cell forabout every 10 endocrine precursor cells, at least about 1 immaturepancreatic islet hormone-expressing cell for about every 5 endocrineprecursor cells, at least about 1 immature pancreatic islethormone-expressing cell for about every 4 endocrine precursor cells, atleast about 1 immature pancreatic islet hormone-expressing cell forabout every 2 endocrine precursor cells, at least about 1 immaturepancreatic islet hormone-expressing cell for about every 1 endocrineprecursor cell, at least about 2 immature pancreatic islethormone-expressing cells for about every 1 endocrine precursor cell, atleast about 4 immature pancreatic islet hormone-expressing cells forabout every 1 endocrine precursor cell, at least about 5 immaturepancreatic islet hormone-expressing cells for about every 1 endocrineprecursor cell, at least about 10 immature pancreatic islethormone-expressing cells for about every 1 endocrine precursor cell, atleast about 20 immature pancreatic islet hormone-expressing cells forabout every 1 endocrine precursor cell, at least about 50 immaturepancreatic islet hormone-expressing cells for about every 1 endocrineprecursor cell, at least about 100 immature pancreatic islethormone-expressing cells for about every 1 endocrine precursor cell, atleast about 1000 immature pancreatic islet hormone-expressing cells forabout every 1 endocrine precursor cell, at least about 10,000 immaturepancreatic islet hormone-expressing cells for about every 1 endocrineprecursor cell, at least about 100,000 immature pancreatic islethormone-expressing cells for about every 1 endocrine precursor cell andat least about 1,000,000 immature pancreatic islet hormone-expressingcells for about every 1 endocrine precursor cell are contemplated.

In some embodiments of the present invention, immature pancreatic islethormone-expressing cells that are produced are derived from humanpluripotent cells, such as human pluripotent stem cells. In certainembodiments, the human pluripotent cells are derived from a morula, theinner cell mass of an embryo or the gonadal ridges of an embryo. Incertain other embodiments, the human pluripotent cells are derived fromthe gonadal or germ tissues of a multicellular structure that hasdeveloped past the embryonic stage.

Further embodiments of the present invention relate to compositions,such as cell cultures or cell populations, comprising human cells,including human immature pancreatic islet hormone-expressing cells,wherein the expression of the MAFB, SYP, CHGA, NKX2.2, ISL1, PAX6,NEUROD, PDX1, HB9, GHRL, IAPP, INS GCG, SST, PP, and/or C-peptide markeris greater than the expression of the NGN3, MAFA, MOX1, CER, POU5F1,AFP, SOX7, SOX1, ZIC1 and/or NFM marker in at least about 2% of thehuman cells. In other embodiments, the expression of the MAFB, SYP,CHGA, NKX2.2, ISL1, PAX6, NEUROD, PDX1, HB9, GHRL, IAPP INS GCG, SST,PP, and/or C-peptide marker is greater than the expression of the NGN3,MAFA, MOX1, CER, POU5F1, AFP, SOX7, SOX1, ZIC1 and/or NFM marker in atleast about 5% of the human cells, in at least about 10% of the humancells, in at least about 15% of the human cells, in at least about 20%of the human cells, in at least about 25% of the human cells, in atleast about 30% of the human cells, in at least about 35% of the humancells, in at least about 40% of the human cells, in at least about 45%of the human cells, in at least about 50% of the human cells, in atleast about 55% of the human cells, in at least about 60% of the humancells, in at least about 65% of the human cells, in at least about 70%of the human cells, in at least about 75% of the human cells, in atleast about 80% of the human cells, in at least about 85% of the humancells, in at least about 90% of the human cells, in at least about 95%of the human cells or in at least about 98% of the human cells. In someembodiments, the percentage of human cells in the cell cultures orpopulations, wherein the expression of MAFB, SYP, CHGA, NKX2.2, ISL1,PAX6, NEUROD, PDX1, HB9, IAPP, INS GCG, SST, PP, and/or C-peptide isgreater than the expression of the NGN3, MAFA, MOX1, CER, POU5F1, AFP,SOX7, SOX1, ZIC1 and/or NFM marker, is calculated without regard tofeeder cells.

Additional embodiments of the present invention relate to compositions,such as cell cultures or cell populations, comprising mammalian cellsdifferentiated from definitive endoderm in vitro, such as human cellsdifferentiated from definitive endoderm in vitro, wherein the expressionof the MAFB, SYP, CHGA, NKX2.2, ISL1, PAX6, NEUROD, PDX1, HB9, GHRL,IAPP, INS GCG, SST, PP, and/or C-peptide is greater than the expressionof the NGN3, MAFA, MOX1, CER, POU5F1, AFP, SOX7, SOX1, ZIC1 and/or NFMmarker in at least about 2% of the cells differentiated from definitiveendoderm in vitro. In other embodiments, the expression of the MAFB,PAX6, GHRL, IAPP, INS, GCG, NKX2.2, SST, PP, CHGA, and/or C-peptide isgreater than the expression of the NGN3, MAFA, MOX1, CER, POU5F1, AFP,SOX7, SOX1, ZIC1 and/or NFM marker in at least about 5% of the cellsdifferentiated from definitive endoderm in vitro, in at least about 10%of the cells differentiated from definitive endoderm in vitro, in atleast about 15% of the cells differentiated from definitive endoderm invitro, in at least about 20% of the cells differentiated from definitiveendoderm in vitro, in at least about 25% of the cells differentiatedfrom definitive endoderm in vitro, in at least about 30% of the cellsdifferentiated from definitive endoderm in vitro, in at least about 35%of the cells differentiated from definitive endoderm in vitro, in atleast about 40% of the cells differentiated from definitive endoderm invitro, in at least about 45% of the cells differentiated from definitiveendoderm in vitro, in at least about 50% of the cells differentiatedfrom definitive endoderm in vitro, in at least about 55% of the cellsdifferentiated from definitive endoderm in vitro, in at least about 60%of the cells differentiated from definitive endoderm in vitro, in atleast about 65% of the cells differentiated from definitive endoderm invitro, in at least about 70% of the cells differentiated from definitiveendoderm in vitro, in at least about 75% of the cells differentiatedfrom definitive endoderm in vitro, in at least about 80% of the cellsdifferentiated from definitive endoderm in vitro, in at least about 85%of the cells differentiated from definitive endoderm in vitro, in atleast about 90% of the cells differentiated from definitive endoderm invitro, in at least about 95% of the cells differentiated from definitiveendoderm in vitro or in at least about 98% of the cells differentiatedfrom definitive endoderm in vitro.

In preferred embodiments of the present invention, cell cultures and/orcell populations of immature pancreatic islet hormone-expressing cellscomprise human immature pancreatic islet hormone-expressing cells, thatare non-recombinant cells. In such embodiments, the cell cultures and/orcell populations are devoid of or substantially free of recombinanthuman immature pancreatic islet hormone-expressing cells.

In some embodiments of the present invention, cell cultures and/or cellpopulations comprising immature pancreatic islet hormone-expressingcells also include a medium which comprises one or more factors selectedfrom nicotinamide, exendin 4, HGF and/or IGF1. In some preferredembodiments, the nicotinamide concentration is at least about 10 mM, theexendin 4 concentration is at least about 40 ng/ml, the HGFconcentration is at least about 25 ng/ml and the IGF1 concentration isat least about 50 ng/ml. In some embodiments, the medium is DMEM.

In certain embodiments of the present invention, cell cultures and/orcell populations comprising immature pancreatic islet hormone-expressingcells also include a medium which comprises one or more secretedhormones selected from ghrelin, insulin, somatostatin and/or glucagon.In other embodiments, the medium comprises C-peptide. In a preferredembodiment, the concentration of one or more secreted hormones orC-peptide in the medium ranges from at least about 1 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA to atleast about 1000 pmol of ghrelin, insulin, somatostatin, glucagon orC-peptide/μg of cellular DNA. In even more preferred embodiments, theconcentration of one or more secreted hormones or C-peptide in themedium is at least about 1 pmol of ghrelin, insulin, somatostatin,glucagon or C-peptide/μg of cellular DNA, at least about 10 pmol ofghrelin, insulin, somatostatin, glucagon or C-peptide/μg of cellularDNA, at least about 25 pmol of ghrelin, insulin, somatostatin, glucagonor C-peptide/μg of cellular DNA, at least about 50 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA, atleast about 75 pmol of ghrelin, insulin, somatostatin, glucagon orC-peptide/μg of cellular DNA, at least about 100 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA, atleast about 150 pmol of ghrelin, insulin, somatostatin, glucagon orC-peptide/μg of cellular DNA, at least about 200 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA, 250pmol of ghrelin, insulin, somatostatin, glucagon or C-peptide/μg ofcellular DNA, at least about 300 pmol of ghrelin, insulin, somatostatin,glucagon or C-peptide/μg of cellular DNA, at least about 350 pmol ofghrelin, insulin, somatostatin, glucagon or C-peptide/μg of cellularDNA, at least about 400 pmol of ghrelin, insulin, somatostatin, glucagonor C-peptide/μg of cellular DNA, at least about 450 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA, atleast about 500 pmol of ghrelin, insulin, somatostatin, glucagon orC-peptide/μg of cellular DNA, at least about 550 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA, atleast about 600 pmol of ghrelin, insulin, somatostatin, glucagon orC-peptide/μg of cellular DNA, 650 pmol of ghrelin, insulin,somatostatin, glucagon or C-peptide/μg of cellular DNA, at least about700 pmol of ghrelin, insulin, somatostatin, glucagon or C-peptide/μg ofcellular DNA, at least about 750 pmol of ghrelin, insulin, somatostatin,glucagon or C-peptide/μg of cellular DNA, at least about 800 pmol ofghrelin, insulin, somatostatin, glucagon or C-peptide/μg of cellularDNA, at least about 850 pmol of ghrelin, insulin, somatostatin, glucagonor C-peptide/μg of cellular DNA, at least about 900 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA, atleast about 950 pmol of ghrelin, insulin, somatostatin, glucagon orC-peptide/μg of cellular DNA or at least about 1000 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA.

In some embodiments of the cell cultures and/or cell populationsdescribed herein, the immature pancreatic islet hormone-expressing cellssecrete more than one pancreatic hormone. In other embodiments of thecell cultures and/or cell populations described herein, the immaturepancreatic islet hormone-expressing cells secrete a single pancreatichormone. In preferred embodiments, the hormone is insulin. In even morepreferred embodiments, the pancreatic islet insulin-expressing cells areresponsive to glucose. In other embodiments, human pancreatic isletinsulin-expressing cells differentiated in vitro secrete insulin in anamount similar to or greater than the amount of insulin secreted bypancreatic beta cells of the human pancreas in vivo.

Using the processes described herein, compositions comprising immaturepancreatic islet hormone-expressing cells substantially free of othercell types can be produced. In some embodiments of the presentinvention, the immature pancreatic islet hormone-expressing cellpopulations or cell cultures produced by the methods described hereinare substantially free of cells that significantly express the NGN3,MAFA, MOX1, CER, POU5F1, AFP, SOX7, SOX1, ZIC1 and/or NFM markers. Insome embodiments of immature pancreatic islet hormone-expressing cellpopulations or cell cultures produced by the methods described herein,the expression of one or more markers selected from the group consistingof MAFB, SYP, CHGA, NKX2.2, ISL1, PAX6, NEUROD, PDX1, HB9, GHRL, IAPP,INS GCG, SST, PP, and/or C-peptide is greater than the expression of oneor more markers selected from the group consisting of NGN3, MAFA, MOX1,CER, POU5F1, AFP, SOX7, SOX1, ZIC1 and/or NFM marker

In one embodiment of the present invention, a description of an immaturepancreatic islet hormone-expressing cell based on the expression ofmarkers is MAFB high; PAX6 high; NKX2.2 high; SYP high; PP high; CHGAhigh; NGN3 low; PAX4 low and MAFA low.

Production of Mature Pancreatic Islet Hormone-Expressing Cells

Embodiments of the present invention relate to methods of producingmature pancreatic islet hormone-expressing cells starting from hESCs. Asdescribed above, pancreatic islet hormone-expressing cells can beproduced by first differentiating hESCs to produce definitive endodermcells, differentiating the definitive endoderm cells to producePDX1-positive foregut endoderm cells, differentiating the PDX1-positiveforegut endoderm cells to produce endocrine precursor cells and thenfurther differentiating the endocrine precursor cells to produceimmature pancreatic islet hormone-expressing cells. In some embodiments,the process is finished by allowing the immature pancreatic islethormone-expressing cells to further differentiate to mature pancreaticislet hormone-expressing cells.

In some embodiments of the present invention, differentiation fromimmature pancreatic islet hormone-expressing cells to mature pancreaticislet hormone-expressing cells proceeds by continuing the incubation ofa culture of immature pancreatic islet hormone-expressing cells with agamma secretase inhibitor for a sufficient time to permit the cells tobecome competent to express at least one mature pancreatic islet cellhormone. In some embodiments, the gamma secretase inhibitor is removedabout 1 day, about 2 days, about 3 days, about 4 days, about 5 days,about 6 days, about 7 days, about 8 days, about 9 days, about 10 days ormore than about 10 days after the induction of endocrine precursorcells. In a preferred embodiment, the gamma secretase inhibitor isN—[N-(3,5-Diflurophenacetyl-L-alanyl)]-S-phenylglycine t-Butyl Ester(DAPT).

Certain processes for the production of mature pancreatic islethormone-expressing cells disclosed herein are mediated by providing acell culture or cell population comprising human endocrine precursorcells and/or immature pancreatic islet hormone-expressing cells with oneor more factors selected from the group consisting of nicotinamide,exendin 4, hepatocyte growth factor (HGF), insulin-like growth factor-1(IGF1). In some embodiments, all four of the above-described factors areprovided together. In some embodiments, one or more of theabove-described factors are provided to the cell culture prior to thedifferentiation of endocrine precursor cells and/or immature pancreaticislet hormone-expressing cells and remain present in the cell cultureduring the differentiation of at least a portion of the cells in thecell culture to mature pancreatic islet hormone-expressing cells. Inother embodiments, one or more of the above-described factors areprovided to the cell culture at or about the time of differentiation ofa substantial portion of the cells to endocrine precursor cells and/orimmature pancreatic islet hormone-expressing cells and remain present inthe cell culture until at least a substantial portion of the cells havedifferentiated into mature pancreatic islet hormone-expressing cells. Insome embodiments of the present invention, one or more of theabove-described factors are provided at the start of the differentiationprocess, for example, at the hESC stage, and remain in the cell culturethroughout the differentiation to mature pancreatic islethormone-expressing cells.

In some processes for the production of mature pancreatic islethormone-expressing cells disclosed herein, nicotinamide is provided tothe cells so that it is present in the cell culture or cell populationat concentrations sufficient to promote differentiation of at least aportion of the endocrine precursor cells and/or immature pancreaticislet hormone-expressing cells to mature pancreatic islethormone-expressing cells. In some embodiments, nicotinamide is presentin the cell culture or cell population at a concentration of at leastabout 0.1 mM, at least about 0.5 mM, at least about 1 mM, at least about2 mM, at least about 3 mM, at least about 4 mM, at least about 5 mM, atleast about 6 mM, at least about 7 mM, at least about 8 mM, at leastabout 9 mM, at least about 10 mM, at least about 11 mM, at least about12 mM, at least about 13 mM, at least about 14 mM, at least about 15 mM,at least about 16 mM, at least about 17 mM, at least about 18 mM, atleast about 19 mM, at least about 20 mM, at least about 25 mM, at leastabout 30 mM, at least about 35 mM, at least about 40 mM, at least about45 mM, at least about 50 mM, at least about 55 mM, at least about 60 mM,at least about 65 mM, at least about 70 mM, at least about 75 mM, atleast about 80 mM, at least about 85 mM, at least about 90 mM, at leastabout 95 mM, at least about 100 mM, at least about 250 mM, at leastabout 500 mM or at least about 1000 mM.

In other processes for the production of mature pancreatic islethormone-expressing cells disclosed herein, exendin 4 is provided to thecells so that it is present in the cell culture or cell population atconcentrations sufficient to promote differentiation of at least aportion of the endocrine precursor cells and/or immature pancreaticislet hormone-expressing cells to pancreatic islet hormone-expressingcells. In some embodiments, exendin 4 is present in the cell culture orcell population at a concentration of at least about 1 ng/ml at leastabout 5 ng/ml, at least about 10 ng/ml, at least about 15 ng/ml, atleast about 20 ng/ml, at least about 25 ng/ml, at least about 30 ng/ml,at least about 35 ng/ml, at least about 40 ng/ml, at least about 45ng/ml, at least about 50 ng/ml, at least about 55 ng/ml, at least about60 ng/ml, at least about 65 ng/ml, at least about 70 ng/ml, at leastabout 75 ng/ml, at least about 80 ng/ml, at least about 85 ng/ml, atleast about 90 ng/ml, at least about 95 ng/ml, at least about 100 ng/ml,at least about 110 ng/ml, at least about 120 ng/ml, at least about 130ng/ml, at least about 140 ng/ml, at least about 150 ng/ml, at leastabout 160 ng/ml, at least about 170 ng/ml, at least about 180 ng/ml, atleast about 190 ng/ml, at least about 200 ng/ml, at least about 250ng/ml, at least about 300 ng/ml, at least about 350 ng/ml, at leastabout 400 ng/ml, at least about 450 ng/ml, at least about 500 ng/ml, atleast about 750 ng/ml, or at least about 1000 ng/ml.

In still other processes for the production of mature pancreatic islethormone-expressing cells disclosed herein, HGF is provided to the cellsso that it is present in the cell culture or cell population atconcentrations sufficient to promote differentiation of at least aportion of the endocrine precursor cells and/or immature pancreaticislet hormone-expressing cells to pancreatic islet hormone-expressingcells. In some embodiments, HGF is present in the cell culture or cellpopulation at a concentration of at least about 1 ng/ml at least about 5ng/ml, at least about 10 ng/ml, at least about 15 ng/ml, at least about20 ng/ml, at least about 25 ng/ml, at least about 30 ng/ml, at leastabout 35 ng/ml, at least about 40 ng/ml, at least about 45 ng/ml, atleast about 50 ng/ml, at least about 55 ng/ml, at least about 60 ng/ml,at least about 65 ng/ml, at least about 70 ng/ml, at least about 75ng/ml, at least about 80 ng/ml, at least about 85 ng/ml, at least about90 ng/ml, at least about 95 ng/ml, at least about 100 ng/ml, at leastabout 110 ng/ml, at least about 120 ng/ml, at least about 130 ng/ml, atleast about 140 ng/ml, at least about 150 ng/ml, at least about 160ng/ml, at least about 170 ng/ml, at least about 180 ng/ml, at leastabout 190 ng/ml, at least about 200 ng/ml, at least about 250 ng/ml, atleast about 300 ng/ml, at least about 350 ng/ml, at least about 400ng/ml, at least about 450 ng/ml, at least about 500 ng/ml, at leastabout 750 ng/ml, or at least about 1000 ng/ml.

In yet other processes for the production of mature pancreatic islethormone-expressing cells disclosed herein, IGF1 is provided to the cellsso that it is present in the cell culture or cell population atconcentrations sufficient to promote differentiation of at least aportion of the endocrine precursor cells and/or immature pancreaticislet hormone-expressing cells to pancreatic islet hormone-expressingcells. In some embodiments, IGF1 is present in the cell culture or cellpopulation at a concentration of at least about 1 ng/ml at least about 5ng/ml, at least about 10 ng/ml, at least about 15 ng/ml, at least about20 ng/ml, at least about 25 ng/ml, at least about 30 ng/ml, at leastabout 35 ng/ml, at least about 40 ng/ml, at least about 45 ng/ml, atleast about 50 ng/ml, at least about 55 ng/ml, at least about 60 ng/ml,at least about 65 ng/ml, at least about 70 ng/ml, at least about 75ng/ml, at least about 80 ng/ml, at least about 85 ng/ml, at least about90 ng/ml, at least about 95 ng/ml, at least about 100 ng/ml, at leastabout 110 ng/ml, at least about 120 ng/ml, at least about 130 ng/ml, atleast about 140 ng/ml, at least about 150 ng/ml, at least about 160ng/ml, at least about 170 ng/ml, at least about 180 ng/ml, at leastabout 190 ng/ml, at least about 200 ng/ml, at least about 250 ng/ml, atleast about 300 ng/ml, at least about 350 ng/ml, at least about 400ng/ml, at least about 450 ng/ml, at least about 500 ng/ml, at leastabout 750 ng/ml, or at least about 1000 ng/ml.

In certain embodiments of the processes for producing mature pancreaticislet hormone-expressing cells as described herein, one or more ofnicotinamide, exendin 4, HGF and IGF1 are provided after one or morepreviously provided differentiation factors have been removed from thecell cultures. In other embodiments, one or more of nicotinamide,exendin 4, HGF and IGF1 are provided to cell culture or cell populationcomprising one or more differentiation factors that were previouslyprovided or provided at about the same time as one or more ofnicotinamide, exendin 4, HGF and IGF1. In preferred embodiments,differentiation factors that were previously provided or provided atabout the same time as one or more of nicotinamide, exendin 4, HGF andIGF1 include, but are not limited to, DAPT, FGF-10, KAAD-cyclopamineactivin A, activin B, BMP4 and/or RA.

In one process for the production of mature pancreatic islethormone-expressing cells from endocrine precursor cells and/or immaturepancreatic islet hormone-expressing cells, a cell culture or a cellpopulation of endocrine precursor cells and/or immature pancreatic islethormone-expressing cells is provided with 10 mM nicotinamide, 40 ng/mlexendin 4, 25 ng/ml HGF and 50 ng/ml IGF1. In a preferred process, thecells are differentiated in Dulbecco's Modified Eagle's Medium (DMEM).

In certain processes for producing mature pancreatic islethormone-expressing cells as described herein, one or more of theabove-mentioned differentiation factors are removed from the cellculture or cell population subsequent to their addition. For example,nicotinamide can be removed within about one day, about two days, aboutthree days, about four days, about five days, about six days, aboutseven days, about eight days, about nine days or about ten days afterthe addition. In some embodiments, the differentiation factors are notremoved from the cell culture.

Cultures of mature pancreatic islet hormone-expressing cells can beproduced in medium containing reduced serum or no serum. Under certainculture conditions, serum concentrations can range from about 0.05% v/vto about 20% v/v. For example, in some differentiation processes, theserum concentration of the medium can be less than about 0.05% (v/v),less than about 0.1% (v/v), less than about 0.2% (v/v), less than about0.3% (v/v), less than about 0.4% (v/v), less than about 0.5% (v/v), lessthan about 0.6% (v/v), less than about 0.7% (v/v), less than about 0.8%(v/v), less than about 0.9% (v/v), less than about 1% (v/v), less thanabout 2% (v/v), less than about 3% (v/v), less than about 4% (v/v), lessthan about 5% (v/v), less than about 6% (v/v), less than about 7% (v/v),less than about 8% (v/v), less than about 9% (v/v), less than about 10%(v/v), less than about 15% (v/v) or less than about 20% (v/v). In someprocesses, mature pancreatic islet hormone-expressing cells are grownwithout serum, without serum replacement and/or without any supplementcontaining insulin or insulin-like growth factor.

In still other processes, mature pancreatic islet hormone-expressingcells are grown in the presence of B27. In such processes, theconcentration of B27 supplement can range from about 0.1% (v/v) to about20% (v/v) or in concentrations greater than about 20% (v/v). In certainprocesses, the concentration of B27 in the medium is about 0.1% (v/v),about 0.2% (v/v), about 0.3% (v/v), about 0.4% (v/v), about 0.5% (v/v),about 0.6% (v/v), about 0.7% (v/v), about 0.8% (v/v), about 0.9% (v/v),about 1% (v/v), about 2% (v/v), about 3% (v/v), about 4% (v/v), about 5%(v/v), about 6% (v/v), about 7% (v/v), about 8% (v/v), about 9% (v/v),about 10% (v/v), about 15% (v/v) or about 20% (v/v). Alternatively, theconcentration of the added B27 supplement can be measured in terms ofmultiples of the strength of a commercially available B27 stocksolution. For example, B27 is available from Invitrogen (Carlsbad,Calif.) as a 50× stock solution. Addition of a sufficient amount of thisstock solution to a sufficient volume of growth medium produces a mediumsupplemented with the desired amount of B27. For example, the additionof 10 ml of 50×B27 stock solution to 90 ml of growth medium wouldproduce a growth medium supplemented with 5×B27. The concentration ofB27 supplement in the medium can be about 0.1×, about 0.2×, about 0.3×,about 0.4×, about 0.5×, about 0.6×, about 0.7×, about 0.8×, about 0.9×,about 1×, about 1.1×, about 1.2×, about 1.3×, about 1.4×, about 1.5×,about 1.6×, about 1.7×, about 1.8×, about 1.9×, about 2×, about 2.5×,about 3×, about 3.5×, about 4×, about 4.5×, about 5×, about 6×, about7×, about 8×, about 9×, about 10×, about 11×, about 12×, about 13×,about 14×, about 15×, about 16×, about 17×, about 18×, about 19×, about20× and greater than about 20×.

Monitoring the Production of Mature Pancreatic Islet Hormone-ExpressingCells

The progression of endocrine precursor cells and immature pancreaticislet hormone-expressing cells to mature pancreatic islethormone-expressing cells can be monitored by determining the expressionof markers characteristic of islet hormone-expressing cells. In someprocesses, the expression of certain markers is determined by detectingthe presence or absence of the marker. Alternatively, the expression ofcertain markers can be determined by measuring the level at which themarker is present in the cells of the cell culture or cell population.In certain processes, the expression of markers characteristic of maturepancreatic islet hormone-expressing cells as well as the lack ofsignificant expression of markers characteristic of hESCs, definitiveendoderm, PDX1-positive foregut endoderm, endocrine precursor, immaturepancreatic islet hormone-expressing, extraembryonic endoderm, mesoderm,ectoderm and/or other cell types is determined.

As described in connection with monitoring the production of other lessdifferentiated cell types of the definitive endoderm lineage,qualitative or semi-quantitative techniques, such as blot transfermethods and immunocytochemistry, can be used to measure markerexpression. Alternatively, marker expression can be accuratelyquantitated through the use of technique such as Q-PCR. Additionally, itwill be appreciated that at the polypeptide level, many of the markersof pancreatic islet hormone-expressing cells are secreted proteins. Assuch, techniques for measuring extracellular marker content, such asELISA, may be utilized.

As set forth in the Examples below, markers of mature pancreatic islethormone-expressing cells include, but are not limited to, ghrelin(GHRL), islet amyloid polypeptide (IAPP), insulin (INS), glucagon (GCG),NKX6 transcription factor related, locus 1 (NKX6.1), somatostatin (SOM;SST), pancreatic polypeptide (PP); synaptophysin (SYP), glucokinase,(GCK), Chromogranin A (CHGA) and/or connecting peptide (C-peptide). Themature pancreatic islet hormone-expressing cells produced by theprocesses described herein express one or more of the above-listedmarkers, thereby producing the corresponding gene products. However, itwill be appreciated that mature pancreatic islet hormone-expressingcells need not express all of the above-described markers. For example,pancreatic islet hormone-expressing cells differentiated from hESCs donot co-express INS and GHRL. This pattern of gene expression isconsistent with the expression of these genes in human fetal pancreas.

Because mature pancreatic islet hormone-expressing cells do notsubstantially express the endocrine precursor cell markers NGN3 andPAX4, transition of endocrine precursor cells to mature pancreatic islethormone-expressing cells can be validated by monitoring the decrease inexpression of NGN3 and PAX4 while monitoring the increase in expressionof one or more of GHRL, IAPP, INS, GCG, NKX6.1, SST, PP, SYP, GCK, CHGAand/or C-peptide. In addition to monitoring the increase and/or decreasein expression of one or more the above-described markers, in someprocesses, the expression of genes indicative hESCs, definitive endodermcells, PDX1-positive foregut endoderm cells endocrine precursor cellsand/or immature pancreatic islet hormone-expressing cells is alsomonitored.

It will be appreciated that GHRL, IAPP, INS, GCG, NKX6.1, SST, PP, SYP,GCK, CHGA and C-peptide marker expression is induced over a range ofdifferent levels in mature pancreatic islet hormone-expressing cellsdepending on the differentiation conditions. As such, in someembodiments described herein, the expression of GHRL, IAPP, INS, GCG,NKX6.1, SST, PP, SYP, GCK, CHGA and/or C-peptide markers in maturepancreatic islet hormone-expressing cells or cell populations is atleast about 2-fold higher to at least about 10,000-fold higher than theexpression of GHRL, IAPP, INS, GCG, NKX6.1, SST, PP, SYP, GCK, CHGAand/or C-peptide markers in non-pancreatic islet hormone-expressingcells or cell populations, for example pluripotent stem cells,definitive endoderm cells, PDX1-positive foregut endoderm cells,endocrine precursor cells, extraembryonic endoderm cells, mesoderm cellsand/or ectoderm cells. In other embodiments, the expression of the GHRL,IAPP, INS, GCG, NKX6.1, SST, PP, SYP, GCK, CHGA and/or C-peptide markersin mature pancreatic islet hormone-expressing cells or cell populationsis at least about 4-fold higher, at least about 6-fold higher, at leastabout 8-fold higher, at least about 10-fold higher, at least about15-fold higher, at least about 20-fold higher, at least about 40-foldhigher, at least about 80-fold higher, at least about 100-fold higher,at least about 150-fold higher, at least about 200-fold higher, at leastabout 500-fold higher, at least about 750-fold higher, at least about1000-fold higher, at least about 2500-fold higher, at least about5000-fold higher, at least about 7500-fold higher or at least about10.000-fold higher than the expression of the GHRL, IAPP, INS, GCG,NKX6.1, SST, PP, SYP, GCK, CHGA and/or C-peptide markers innon-pancreatic islet hormone-expressing cells or cell populations, forexample pluripotent stem cells, definitive endoderm cells, PDX1-positiveforegut endoderm cells, endocrine precursor cells, extraembryonicendoderm cells, mesoderm cells and/or ectoderm cells. In someembodiments, the expression of the GHRL, IAPP, INS, GCG, NKX6.1, SST,PP, SYP, GCK, CHGA and/or C-peptide markers in mature pancreatic islethormone-expressing cells or cell populations is infinitely higher thanthe expression of the GHRL, IAPP, INS, GCG, NKX6.1, SST, PP, SYP, GCK,CHGA and/or C-peptide markers in non-pancreatic islet hormone-expressingcells or cell populations, for example pluripotent stem cells,definitive endoderm cells, PDX1-positive foregut endoderm cells,endocrine precursor cells, extraembryonic endoderm cells, mesoderm cellsand/or ectoderm cells.

It will also be appreciated that the MAFA marker expression increases,for example, in cells that co-express INS, over a range of differentlevels in mature pancreatic islet hormone-expressing cells. Depending onthe differentiation conditions, MAFA marker expression is induced over arange of different levels in mature pancreatic islet hormone-expressingcells. As such, in some embodiments described herein, the expression ofthe MAFA marker in mature pancreatic islet hormone-expressing cells orcell populations is at least about 2-fold higher to at least about10.000-fold higher than the expression of MAFA marker expression inimmature pancreatic islet hormone-expressing cells or in non-pancreaticislet hormone-expressing cell populations, for example pluripotent stemcells, definitive endoderm cells, PDX1-positive foregut endoderm cells,endocrine precursor cells, extraembryonic endoderm cells, mesoderm cellsand/or ectoderm cells. In other embodiments, the expression of the MAFAmarker in mature pancreatic islet hormone-expressing cells or cellpopulations is at least about 4-fold higher, at least about 6-foldhigher, at least about 8-fold higher, at least about 10-fold higher, atleast about 15-fold higher, at least about 20-fold higher, at leastabout 40-fold higher, at least about 80-fold higher, at least about100-fold higher, at least about 150-fold higher, at least about 200-foldhigher, at least about 500-fold higher, at least about 750-fold higher,at least about 1000-fold higher, at least about 2500-fold higher, atleast about 5000-fold higher, at least about 7500-fold higher or atleast about 10.000-fold higher than the expression of the MAFA markersin immature pancreatic islet hormone-expressing cells or non-pancreaticislet hormone-expressing cells, for example pluripotent stem cells,definitive endoderm cells, PDX1-positive foregut endoderm cells,endocrine precursor cells, extraembryonic endoderm cells, mesoderm cellsand/or ectoderm cells. In some embodiments, the expression of the MAFAmarker in mature pancreatic islet hormone-expressing cells or cellpopulations is infinitely higher than the expression of the MAFA markerin immature pancreatic islet hormone-expressing cells or in othernon-pancreatic islet hormone-expressing cells, for example pluripotentstem cells, definitive endoderm cells, PDX1-positive foregut endodermcells, endocrine precursor cells, extraembryonic endoderm cells,mesoderm cells and/or ectoderm cells.

It will also be appreciated that NGN3 and/or PAX4 marker expressiondecreases over a range of different levels in mature pancreatic islethormone-expressing cells depending on the differentiation conditions. Assuch, in some embodiments described herein, the expression of NGN3and/or PAX4 markers in mature pancreatic islet hormone-expressing cellsor cell populations is at least about 2-fold lower to at least about10.000-fold lower than the expression of NGN3 and/or PAX4 markers inendocrine precursor cells. In other embodiments, the expression of theNGN3 and/or PAX4 markers in mature pancreatic islet hormone-expressingcells or cell populations is at least about 4-fold lower, at least about6-fold lower, at least about 8-fold lower, at least about 10-fold lower,at least about 15-fold lower, at least about 20-fold lower, at leastabout 40-fold lower, at least about 80-fold lower, at least about100-fold lower, at least about 150-fold lower, at least about 200-foldlower, at least about 500-fold lower, at least about 750-fold lower, atleast about 1000-fold lower, at least about 2500-fold lower, at leastabout 5000-fold lower, at least about 7500-fold lower or at least about10.000-fold lower than the expression of the NGN3 and/or PAX4 markers inendocrine precursor cells. In some embodiments, the NGN3 and/or PAX4markers are not substantially expressed in mature pancreatic islethormone-expressing cells or cell populations.

In some embodiments of the processes described herein, the amount ofhormone release from cells and/or cell populations can be determined.For example, the amount of insulin release, glucagon release,somatostatin release and/or ghrelin release can be monitored. In apreferred embodiment, the amount of insulin secreted in response toglucose (GSIS) is measured. In still other embodiments, secretedbreakdown or by-products produced by the mature pancreatic islethormone-expressing cells, such as c-peptide and islet amyloid protein,can be monitored.

It will be appreciated that methods of measuring the expression ofsecreted proteins are well known in the art. For example, an antibodyagainst one or more hormones produced by islet cells can be used inELISA assays.

In some embodiments of the present invention, insulin release by maturepancreatic islet hormone-expressing cells is measured by measuringC-peptide release. C-peptide is a cleavage product that is produced inequal molar amounts to insulin during the maturation of pro-insulin.Measuring C-peptide is advantageous because its half life is longer thanthat of insulin. Methods of measuring C-peptide release are well knownin the art, for example, ELISA using anti-C-peptide monoclonal antibody(Linco Research, St. Louis, Mo.). In some embodiments of the presentinvention, mature pancreatic islet hormone-expressing cells producedfrom hESCs secrete at least about 50 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 100 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 150 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 200 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 250 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 300 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 350 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 400 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 450 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 500 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 550 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 600 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 650 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 700 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 750 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 800 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 850 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 900 pmol of C-peptide (insulin)/μg ofcellular DNA, at least about 950 pmol of C-peptide (insulin)/μg ofcellular DNA or at least about 1000 pmol of C-peptide (insulin)/μg ofcellular DNA. In preferred embodiments, the mature pancreatic islethormone-expressing cells are cells that secrete a single type of isletcell hormone (for example, the cells secrete only insulin). In certainpreferred embodiments, the insulin is secreted in response to glucose.In other embodiments, the mature pancreatic islet hormone-expressingcells are cells that secrete insulin in addition to one or more isletcell hormones, for example, somatostatin, glucagon and/or ghrelin.

In some embodiments, mature pancreatic islet hormone-expressing cellsprocess greater than about 80% of the insulin produced by said maturepancreatic islet hormone-expressing cells. In some embodiments, maturepancreatic islet hormone-expressing cells process greater than about85%, greater than about 90%, greater than about 91%, greater than about92%, greater than about 93%, greater than about 94%, greater than about95%, greater than about 96%, greater than about 97%, greater than about98% or greater than about 99% of the insulin produced by said maturepancreatic islet hormone-expressing cells.

In other embodiments of the present invention, mature pancreatic islethormone-expressing cells produced from hESCs secrete at least about 50pmol of glucagon/μg of cellular DNA, at least about 100 pmol ofglucagon/μg of cellular DNA, at least about 150 pmol of glucagon/μg ofcellular DNA, at least about 200 pmol of glucagon/μg of cellular DNA, atleast about 250 pmol of glucagon/μg of cellular DNA, at least about 300pmol of glucagon/μg of cellular DNA, at least about 350 pmol ofglucagon/μg of cellular DNA, at least about 400 pmol of glucagon/μg ofcellular DNA, at least about 450 pmol of glucagon/μg of cellular DNA, atleast about 500 pmol of glucagon/μg of cellular DNA, at least about 550pmol of glucagon/μg of cellular DNA, at least about 600 pmol ofglucagon/μg of cellular DNA, at least about 650 pmol of glucagon/μg ofcellular DNA, at least about 700 pmol of glucagon/μg of cellular DNA, atleast about 750 pmol of glucagon/μg of cellular DNA, at least about 800pmol of glucagon/μg of cellular DNA, at least about 850 pmol ofglucagon/μg of cellular DNA, at least about 900 pmol of glucagon/μg ofcellular DNA, at least about 950 pmol of glucagon/μg of cellular DNA orat least about 1000 pmol of glucagon/μg of cellular DNA. In preferredembodiments, the mature pancreatic islet hormone-expressing cells arecells that secrete a single type of islet cell hormone (for example, thecells secrete only glucagon). In other embodiments, the maturepancreatic islet hormone-expressing cells are cells that secreteglucagon in addition to one or more islet cell hormones, for example,ghrelin, somatostatin and insulin.

In still other embodiments of the present invention, mature pancreaticislet hormone-expressing cells produced from hESCs secrete at leastabout 50 pmol of somatostatin/μg of cellular DNA, at least about 100pmol of somatostatin/μg of cellular DNA, at least about 150 pmol ofsomatostatin/μg of cellular DNA, at least about 200 pmol ofsomatostatin/μg of cellular DNA, at least about 250 pmol ofsomatostatin/μg of cellular DNA, at least about 300 pmol ofsomatostatin/μg of cellular DNA, at least about 350 pmol ofsomatostatin/μg of cellular DNA, at least about 400 pmol ofsomatostatin/μg of cellular DNA, at least about 450 pmol ofsomatostatin/μg of cellular DNA, at least about 500 pmol ofsomatostatin/μg of cellular DNA, at least about 550 pmol ofsomatostatin/μg of cellular DNA, at least about 600 pmol ofsomatostatin/μg of cellular DNA, at least about 650 pmol ofsomatostatin/μg of cellular DNA, at least about 700 pmol ofsomatostatin/μg of cellular DNA, at least about 750 pmol ofsomatostatin/μg of cellular DNA, at least about 800 pmol ofsomatostatin/μg of cellular DNA, at least about 850 pmol ofsomatostatin/μg of cellular DNA, at least about 900 pmol ofsomatostatin/μg of cellular DNA, at least about 950 pmol ofsomatostatin/μg of cellular DNA or at least about 1000 pmol ofsomatostatin/μg of cellular DNA. In preferred embodiments, the maturepancreatic islet hormone-expressing cells are cells that secrete asingle type of islet cell hormone (for example, the cells secrete onlysomatostatin). In other embodiments, the mature pancreatic islethormone-expressing cells are cells that secrete somatostatin in additionto one or more islet cell hormones, for example, ghrelin, glucagon andinsulin.

In other embodiments of the present invention, mature pancreatic islethormone-expressing cells produced from hESCs secrete at least about 50pmol of ghrelin/μg of cellular DNA, at least about 100 pmol ofghrelin/μg of cellular DNA, at least about 150 pmol of ghrelin/μg ofcellular DNA, at least about 200 pmol of ghrelin/μg of cellular DNA, atleast about 250 pmol of ghrelin/μg of cellular DNA, at least about 300pmol of ghrelin/μg of cellular DNA, at least about 350 pmol ofghrelin/μg of cellular DNA, at least about 400 pmol of ghrelin/μg ofcellular DNA, at least about 450 pmol of ghrelin/μg of cellular DNA, atleast about 500 pmol of ghrelin/μg of cellular DNA, at least about 550pmol of ghrelin/μg of cellular DNA, at least about 600 pmol ofghrelin/μg of cellular DNA, at least about 650 pmol of ghrelin/μg ofcellular DNA, at least about 700 pmol of ghrelin/μg of cellular DNA, atleast about 750 pmol of ghrelin/μg of cellular DNA, at least about 800pmol of ghrelin/μg of cellular DNA, at least about 850 pmol ofghrelin/μg of cellular DNA, at least about 900 pmol of ghrelin/μg ofcellular DNA, at least about 950 pmol of ghrelin/μg of cellular DNA orat least about 1000 pmol of ghrelin/μg of cellular DNA. In preferredembodiments, the mature pancreatic islet hormone-expressing cells arecells that secrete a single type of islet cell hormone (for example, thecells secrete only ghrelin). In other embodiments, the mature pancreaticislet hormone-expressing cells are cells that secrete ghrelin inaddition to one or more islet cell hormones.

Enrichment Isolation and/or Purification of Mature Pancreatic IsletHormone-Expressing Cells

Mature pancreatic islet hormone-expressing cells produced by any of theabove-described processes can be enriched, isolated and/or purified byusing an affinity tag that is specific for such cells. Examples ofaffinity tags specific for mature pancreatic islet hormone-expressingcells are antibodies, ligands or other binding agents that are specificto a marker molecule, such as a polypeptide, that is present on the cellsurface of mature pancreatic islet hormone-expressing cells but which isnot substantially present on other cell types that would be found in acell culture produced by the methods described herein. In someprocesses, an antibody which binds to a cell surface antigen on humanpancreatic islet cells is used as an affinity tag for the enrichment,isolation or purification of mature pancreatic islet hormone-expressingcells produced by in vitro methods, such as the methods describedherein. Such antibodies are known and commercially available. Forexample, a monoclonal antibody that is highly specific for a cellsurface marker on human islet cells is available from USBiological,Swampscott, Mass. (Catalog Number P2999-40). Other examples include thehighly specific monoclonal antibodies to glycoproteins located on thepancreatic islet cell surface, which have been described by Srikanta, etal., (1987) Endocrinology, 120:2240-2244, the disclosure of which isincorporated herein by reference in its entirety. A preferred example ofan affinity tag for mature pancreatic islet hormone-expressing cells,such as those derived in vitro from human pluripotent cells, is NCAM.Antibodies against NCAM are commercially available, for example fromAbcam (Cambridge, Mass.).

The skilled artisan will readily appreciate that the processes formaking and using antibodies for the enrichment, isolation and/orpurification of immature pancreatic islet hormone-expressing are alsoreadily adaptable for the enrichment, isolation and/or purification ofpancreatic islet hormone-expressing cells. For example, in someembodiments, the reagent, such as an NCAM antibody, is incubated with acell culture containing mature pancreatic islet hormone-expressingcells, wherein the cell culture has been treated to reduce intercellularand substrate adhesion. The cells are then washed, centrifuged andresuspended. (WE DO NOT USE A SECONDARY ANTIBODY. WE USE A DIRECTFLUORESCENT COJUGATED NCAM ANTIBODY. The cell suspension is thenincubated with a secondary antibody, such as an FITC-conjugated antibodythat is capable of binding to the primary antibody. The cells are thenwashed, centrifuged and resuspended in buffer. The cell suspension isthen analyzed and sorted using a fluorescence activated cell sorter(FACS). Antibody-bound, fluorescent cells are collected separately fromnon-bound, non-fluorescent, thereby resulting in the isolation of suchcell types.

In preferred embodiments of the processes described herein, the isolatedcell compositions can be further purified by using an alternateaffinity-based method or by additional rounds of sorting using the sameor different markers that are specific for mature pancreatic islethormone-expressing cells. For example, in some embodiments, FACS sortingis used to first isolate NCAM-positive mature pancreatichormone-expressing cells from NCAM negative cells from cell populationscomprising mature pancreatic hormone-expressing cells. Sorting the NCAMpositive cells again using FACS to isolate cells that are NCAM positiveenriches the cell population for mature pancreatic hormone expressingcells that express markers characteristic of this cell type, includingNKX6.1, MAFA, ISL1 or PAX6. In other embodiments, FACS sorting is usedto separate cells by negatively sorting for a marker that is present onmost cells in the cell population other than the mature pancreatic islethormone-expressing cells. An example of such a negative sort is the useof CD133, which is a marker that is not substantially expressed on thesurface of mature pancreatic islet hormone-expressing cells in the NCAMpositive cell population after the first round of enrichment but whichis expressed on many other NCAM positive cells in this cell population.

In some embodiments of the processes described herein, mature pancreaticislet hormone-expressing cells are fluorescently labeled without the useof an antibody then isolated from non-labeled cells by using afluorescence activated cell sorter (FACS). In such embodiments, anucleic acid encoding GFP, YFP or another nucleic acid encoding anexpressible fluorescent marker gene, such as the gene encodingluciferase, is used to label mature pancreatic islet hormone-expressingcells using the methods described above. For example, in someembodiments, at least one copy of a nucleic acid encoding GFP or abiologically active fragment thereof is introduced into a pluripotentcell, preferably a human embryonic stem cell, downstream of the NKX6.1promoter such that the expression of the GFP gene product orbiologically active fragment thereof is under control of the NKX6.1promoter. In some embodiments, the entire coding region of the nucleicacid, which encodes NKX6.1, is replaced by a nucleic acid encoding GFPor a biologically active fragment thereof. In other embodiments, thenucleic acid encoding GFP or a biologically active fragment thereof isfused in frame with at least a portion of the nucleic acid encodingNKX6.1, thereby generating a fusion protein. In such embodiments, thefusion protein retains a fluorescent activity similar to GFP.

It will be appreciated that promoters other than the NKX6.1 promoter canbe used provided that the promoter corresponds to a marker that isexpressed in pancreatic islet hormone-expressing cells. One exemplarymarker is NKX2.2.

Fluorescently marked cells, such as the above-described pluripotentcells, are differentiated to mature pancreatic islet hormone-expressingcells as described previously above. Because mature pancreatic islethormone-expressing cells express the fluorescent marker gene, whereasother cell types do not, pancreatic islet hormone-expressing cells canbe separated from the other cell types. In some embodiments, cellsuspensions comprising a mixture of fluorescently-labeled maturepancreatic islet hormone-expressing cells and unlabeled non-pancreaticislet hormone-expressing cells are sorted using a FACS. Maturepancreatic islet hormone-expressing cells are collected separately fromnon-fluorescing cells, thereby resulting in the isolation of maturepancreatic islet hormone-expressing cells. If desired, the isolated cellcompositions can be further purified by additional rounds of sortingusing the same or different markers that are specific for maturepancreatic islet hormone-expressing cells.

In preferred processes, mature pancreatic islet hormone-expressing cellsare enriched, isolated and/or purified from other non-pancreatic islethormone-expressing cells after the cultures are induced to differentiatetowards mature pancreatic islet hormone-expressing cells.

In addition to the procedures just described, mature pancreatic islethormone-expressing cells may also be isolated by other techniques forcell isolation. Additionally, mature pancreatic islet hormone-expressingcells may also be enriched or isolated by methods of serial subculturein growth conditions which promote the selective survival or selectiveexpansion of the pancreatic islet hormone-expressing cells.

Using the methods described herein, enriched, isolated and/or purifiedpopulations of mature pancreatic islet hormone-expressing cells and ortissues can be produced in vitro from pluripotent cell cultures or cellpopulations, such as stem cell cultures or populations, which haveundergone sufficient differentiation to produce at least some maturepancreatic islet hormone-expressing cells. In a preferred method, thecells are directed to differentiate primarily into mature pancreaticislet hormone-expressing cells. Some preferred enrichment, isolationand/or purification methods relate to the in vitro production of maturepancreatic islet hormone-expressing cells from human embryonic stemcells.

Using the methods described herein, cell populations or cell culturescan be enriched in mature pancreatic islet hormone-expressing cellcontent by at least about 2- to about 1000-fold as compared to untreatedor less specifically differentiated cell populations or cell cultures.In some embodiments, mature pancreatic islet hormone-expressing cellscan be enriched by at least about 5- to about 500-fold as compared tountreated or less specifically differentiated cell populations or cellcultures. In other embodiments, mature pancreatic islethormone-expressing cells can be enriched from at least about 10- toabout 200-fold as compared to untreated or less specificallydifferentiated cell populations or cell cultures. In still otherembodiments, mature pancreatic islet hormone-expressing cells can beenriched from at least about 20- to about 100-fold as compared tountreated or less specifically differentiated cell populations or cellcultures. In yet other embodiments, mature pancreatic islethormone-expressing cells can be enriched from at least about 40- toabout 80-fold as compared to untreated or less specificallydifferentiated cell populations or cell cultures. In certainembodiments, mature pancreatic islet hormone-expressing cells can beenriched from at least about 2- to about 20-fold as compared tountreated or less specifically differentiated cell populations or cellcultures.

Compositions Comprising Pancreatic Islet Hormone-Expressing Cells

Some embodiments of the present invention relate to cell compositions,such as cell cultures or cell populations, comprising mature pancreaticislet hormone-expressing cells, wherein the mature pancreatic islethormone-expressing cells are cells, which have been derived from humanpluripotent cells in vitro, which express one or more pancreatichormones and which have at least some of the functions of humanpancreatic islet cells. In accordance with certain embodiments, thepancreatic islet hormone-expressing cells are mammalian cells, and in apreferred embodiment, such cells are human cells.

Other embodiments of the present invention relate to compositions, suchas cell cultures or cell populations, comprising mature pancreatic islethormone-expressing cells and cells that are less specificallydifferentiated than mature pancreatic islet hormone-expressing cells. Insuch embodiments, cells that are less specifically differentiated thanmature pancreatic islet hormone-expressing cells comprise less thanabout 90%, less than about 85%, less than about 80%, less than about75%, less than about 70%, less than about 65%, less than about 60%, lessthan about 55%, less than about 50%, less than about 45%, less thanabout 40%, less than about 35%, less than about 30%, less than about25%, less than about 20%, less than about 15%, less than about 12%, lessthan about 10%, less than about 8%, less than about 6%, less than about5%, less than about 4%, less than about 3%, less than about 2% or lessthan about 1% of the total cells in the culture.

Certain other embodiments of the present invention relate tocompositions, such as cell cultures or cell populations, comprisingmature pancreatic islet hormone-expressing cells and cells of one ormore cell types selected from the group consisting of hESCs,pre-primitive streak cells, mesendoderm cells, definitive endodermcells, PDX1-negative foregut endoderm cells, PDX1-positive foregutendoderm cells (PDX1-positive pancreatic endoderm cells), endocrineprecursor cells and mesoderm cells. In some embodiments, hESCs compriseless than about 25%, less than about 20%, less than about 15%, less thanabout 10%, less than about 5%, less than about 4%, less than about 3%,less than about 2% or less than about 1% of the total cells in theculture. In certain embodiments, pre-primitive streak cells compriseless than about 25%, less than about 20%, less than about 15%, less thanabout 10%, less than about 5%, less than about 4%, less than about 3%,less than about 2% or less than about 1% of the total cells in theculture. In other embodiments, mesendoderm cells comprise less thanabout 25%, less than about 20%, less than about 15%, less than about10%, less than about 5%, less than about 4%, less than about 3%, lessthan about 2% or less than about 1% of the total cells in the culture.In still other embodiments, definitive endoderm cells comprise less thanabout 90%, less than about 85%, less than about 80%, less than about75%, less than about 70%, less than about 65%, less than about 60%, lessthan about 55%, less than about 50%, less than about 45%, less thanabout 40%, less than about 35%, less than about 30%, less than about25%, less than about 20%, less than about 15%, less than about 12%, lessthan about 10%, less than about 8%, less than about 6%, less than about5%, less than about 4%, less than about 3%, less than about 2% or lessthan about 1% of the total cells in the culture. In yet otherembodiments, PDX1-negative foregut endoderm cells comprise less thanabout 90%, less than about 85%, less than about 80%, less than about75%, less than about 70%, less than about 65%, less than about 60%, lessthan about 55%, less than about 50%, less than about 45%, less thanabout 40%, less than about 35%, less than about 30%, less than about25%, less than about 20%, less than about 15%, less than about 12%, lessthan about 10%, less than about 8%, less than about 6%, less than about5%, less than about 4%, less than about 3%, less than about 2% or lessthan about 1% of the total cells in the culture. In certain embodiments,PDX1-positive foregut endoderm cells comprise less than about 90%, lessthan about 85%, less than about 80%, less than about 75%, less thanabout 70%, less than about 65%, less than about 60%, less than about55%, less than about 50%, less than about 45%, less than about 40%, lessthan about 35%, less than about 30%, less than about 25%, less thanabout 20%, less than about 15%, less than about 12%, less than about10%, less than about 8%, less than about 6%, less than about 5%, lessthan about 4%, less than about 3%, less than about 2% or less than about1% of the total cells in the culture. In other embodiments, endocrineprecursor cells comprise less than about 90%, less than about 85%, lessthan about 80%, less than about 75%, less than about 70%, less thanabout 65%, less than about 60%, less than about 55%, less than about50%, less than about 45%, less than about 40%, less than about 35%, lessthan about 30%, less than about 25%, less than about 20%, less thanabout 15%, less than about 12%, less than about 10%, less than about 8%,less than about 6%, less than about 5%, less than about 4%, less thanabout 3%, less than about 2% or less than about 1% of the total cells inthe culture. In still other embodiments, mesoderm cells comprise lessthan about 90%, less than about 85%, less than about 80%, less thanabout 75%, less than about 70%, less than about 65%, less than about60%, less than about 55%, less than about 50%, less than about 45%, lessthan about 40%, less than about 35%, less than about 30%, less thanabout 25%, less than about 20%, less than about 15%, less than about12%, less than about 10%, less than about 8%, less than about 6%, lessthan about 5%, less than about 4%, less than about 3%, less than about2% or less than about 1% of the total cells in the culture.

Other embodiments of the present invention relate to compositions, suchas cell cultures or cell populations, comprising mature pancreatic islethormone-expressing cells and immature pancreatic islethormone-expressing cells. In such embodiments, immature pancreatic islethormone-expressing cells comprise less than about 90%, less than about85%, less than about 80%, less than about 75%, less than about 70%, lessthan about 65%, less than about 60%, less than about 55%, less thanabout 50%, less than about 45%, less than about 40%, less than about35%, less than about 30%, less than about 25%, less than about 20%, lessthan about 15%, less than about 12%, less than about 10%, less thanabout 8%, less than about 6%, less than about 5%, less than about 4%,less than about 3%, less than about 2% or less than about 1% of thetotal cells in the culture.

Additional embodiments of the present invention relate to compositions,such as cell cultures or cell populations, produced by the processesdescribed herein and which comprise mature pancreatic islethormone-expressing cells as the majority cell type. In some embodiments,the processes described herein produce cell cultures and/or cellpopulations comprising at least about 99%, at least about 98%, at leastabout 97%, at least about 96%, at least about 95%, at least about 94%,at least about 93%, at least about 92%, at least about 91%, at leastabout 90%, at least about 89%, at least about 88%, at least about 87%,at least about 86%, at least about 85%, at least about 84%, at leastabout 83%, at least about 82%, at least about 81%, at least about 80%,at least about 79%, at least about 78%, at least about 77%, at leastabout 76%, at least about 75%, at least about 74%, at least about 73%,at least about 72%, at least about 71%, at least about 70%, at leastabout 69%, at least about 68%, at least about 67%, at least about 66%,at least about 65%, at least about 64%, at least about 63%, at leastabout 62%, at least about 61%, at least about 60%, at least about 59%,at least about 58%, at least about 57%, at least about 56%, at leastabout 55%, at least about 54%, at least about 53%, at least about 52%,at least about 51% or at least about 50% mature pancreatic islethormone-expressing cells. In preferred embodiments, the cells of thecell cultures or cell populations comprise human cells. In otherembodiments, the processes described herein produce cell cultures orcell populations comprising at least about 50%, at least about 45%, atleast about 40%, at least about 35%, at least about 30%, at least about25%, at least about 24%, at least about 23%, at least about 22%, atleast about 21%, at least about 20%, at least about 19%, at least about18%, at least about 17%, at least about 16%, at least about 15%, atleast about 14%, at least about 13%, at least about 12%, at least about11%, at least about 10%, at least about 9%, at least about 8%, at leastabout 7%, at least about 6%, at least about 5%, at least about 4%, atleast about 3%, at least about 2% or at least about 1% mature pancreaticislet hormone-expressing cells. In preferred embodiments, the cells ofthe cell cultures or cell populations comprise human cells. In someembodiments, the percentage of mature pancreatic islethormone-expressing cells in the cell cultures or populations iscalculated without regard to the feeder cells remaining in the culture.

Still other embodiments of the present invention relate to compositions,such as cell cultures or cell populations, comprising mixtures of maturepancreatic islet hormone-expressing cells and endocrine precursor cellsand/or immature pancreatic islet hormone-expressing cells. For example,cell cultures or cell populations comprising at least about 5 maturepancreatic islet hormone-expressing cells for about every 95 endocrineprecursor and/or immature pancreatic islet hormone-expressing cells canbe produced. In other embodiments, cell cultures or cell populationscomprising at least about 95 mature pancreatic islet hormone-expressingcells for about every 5 endocrine precursor cells and/or immaturepancreatic islet hormone-expressing cells can be produced. Additionally,cell cultures or cell populations comprising other ratios of maturepancreatic islet hormone-expressing cells to endocrine precursor and/orimmature pancreatic islet hormone-expressing cells are contemplated. Forexample, compositions comprising at least about 1 mature pancreaticislet hormone-expressing cell for about every 1,000,000 endocrineprecursor cells and/or immature pancreatic islet hormone-expressingcells, at least about 1 mature pancreatic islet hormone-expressing cellfor about every 100,000 endocrine precursor cells and/or immaturepancreatic islet hormone-expressing cells, at least about 1 maturepancreatic islet hormone-expressing cell for about every 10,000endocrine precursor cells and/or immature pancreatic islethormone-expressing cells, at least about 1 mature pancreatic islethormone-expressing cell for about every 1000 endocrine precursor cellsand/or immature pancreatic islet hormone-expressing cells, at leastabout 1 mature pancreatic islet hormone-expressing cell for about every500 endocrine precursor cells and/or immature pancreatic islethormone-expressing cells, at least about 1 mature pancreatic islethormone-expressing cell for about every 100 endocrine precursor cellsand/or immature pancreatic islet hormone-expressing cells, at leastabout 1 mature pancreatic islet hormone-expressing cell for about every10 endocrine precursor cells and/or immature pancreatic islethormone-expressing cells, at least about 1 mature pancreatic islethormone-expressing cell for about every 5 endocrine precursor cellsand/or immature pancreatic islet hormone-expressing cells, at leastabout 1 mature pancreatic islet hormone-expressing cell for about every4 endocrine precursor cells and/or immature pancreatic islethormone-expressing cells, at least about 1 mature pancreatic islethormone-expressing cell for about every 2 endocrine precursor cellsand/or immature pancreatic islet hormone-expressing cells, at leastabout 1 mature pancreatic islet hormone-expressing cell for about every1 endocrine precursor cell and/or immature pancreatic islethormone-expressing cell, at least about 2 mature pancreatic islethormone-expressing cells for about every 1 endocrine precursor celland/or immature pancreatic islet hormone-expressing cell, at least about4 mature pancreatic islet hormone-expressing cells for about every 1endocrine precursor cell and/or immature pancreatic islethormone-expressing cell, at least about 5 mature pancreatic islethormone-expressing cells for about every 1 endocrine precursor celland/or immature pancreatic islet hormone-expressing cell, at least about10 mature pancreatic islet hormone-expressing cells for about every 1endocrine precursor cell and/or immature pancreatic islethormone-expressing cell, at least about 20 mature pancreatic islethormone-expressing cells for about every 1 endocrine precursor celland/or immature pancreatic islet hormone-expressing cell, at least about50 mature pancreatic islet hormone-expressing cells for about every 1endocrine precursor cell and/or immature pancreatic islethormone-expressing cell, at least about 100 mature pancreatic islethormone-expressing cells for about every 1 endocrine precursor celland/or immature pancreatic islet hormone-expressing cell, at least about1000 mature pancreatic islet hormone-expressing cells for about every 1endocrine precursor cell and/or immature pancreatic islethormone-expressing cell, at least about 10,000 mature pancreatic islethormone-expressing cells for about every 1 endocrine precursor celland/or immature pancreatic islet hormone-expressing cell, at least about100,000 mature pancreatic islet hormone-expressing cells for about every1 endocrine precursor cell and/or immature pancreatic islethormone-expressing cell and at least about 1,000,000 mature pancreaticislet hormone-expressing cells for about every 1 endocrine precursorcell and/or immature pancreatic islet hormone-expressing cell arecontemplated.

In some embodiments of the present invention, the mature pancreaticislet hormone-expressing cells produced are derived from humanpluripotent cells, such as human pluripotent stem cells. In certainembodiments, the human pluripotent cells are derived from a morula, theinner cell mass of an embryo or the gonadal ridges of an embryo. Incertain other embodiments, the human pluripotent cells are derived fromthe gonadal or germ tissues of a multicellular structure that hasdeveloped past the embryonic stage.

Further embodiments of the present invention relate to compositions,such as cell cultures or cell populations, comprising human cells,including human mature pancreatic islet hormone-expressing cells,wherein the expression of the GHRL, IAPP, INS, GCG, NKX6.1, SS, PP, SYP,GCK, CHGA and/or C-peptide marker is greater than the expression of theAFP, SOX7, SOX1, ZIC1 and/or NFM marker in at least about 2% of thehuman cells. In other embodiments, the expression of the GHRL, IAPP,INS, GCG, NKX6.1, SS, PP, SYP, GCK, CHGA and/or C-peptide marker isgreater than the expression of the AFP, SOX7, SOX1, ZIC1, NFM, NGN3and/or PAX4 marker in at least about 5% of the human cells, in at leastabout 10% of the human cells, in at least about 15% of the human cells,in at least about 20% of the human cells, in at least about 25% of thehuman cells, in at least about 30% of the human cells, in at least about35% of the human cells, in at least about 40% of the human cells, in atleast about 45% of the human cells, in at least about 50% of the humancells, in at least about 55% of the human cells, in at least about 60%of the human cells, in at least about 65% of the human cells, in atleast about 70% of the human cells, in at least about 75% of the humancells, in at least about 80% of the human cells, in at least about 85%of the human cells, in at least about 90% of the human cells, in atleast about 95% of the human cells or in at least about 98% of the humancells. In some embodiments, the percentage of human cells in the cellcultures or populations, wherein the expression of GHRL, IAPP, INS, GCG,NKX6.1, SS, PP, SYP, GCK, CHGA and/or C-peptide is greater than theexpression of the AFP, SOX7, SOX1, ZIC1, NFM, NGN3 and/or PAX4 marker,is calculated without regard to feeder cells.

Additional embodiments of the present invention relate to compositions,such as cell cultures or cell populations, comprising mammalian cellsdifferentiated from definitive endoderm in vitro, such as human cellsdifferentiated from definitive endoderm in vitro, wherein the expressionof the GHRL, IAPP, INS, GCG, NKX6.1, SS, PP, SYP, GCK, CHGA and/orC-peptide marker is greater than the expression of the AFP, SOX7, SOX1,ZIC1, NFM, NGN3 and/or PAX4 marker in at least about 2% of the cellsdifferentiated from definitive endoderm in vitro. In other embodiments,the expression of the GHRL, IAPP, INS, GCG, NKX6.1, SS, PP, SYP, GCK,CHGA and/or C-peptide marker is greater than the expression of the AFP,SOX7, SOX1, ZIC1, NFM, NGN3 and/or PAX4 marker in at least about 5% ofthe cells differentiated from definitive endoderm in vitro, in at leastabout 10% of the cells differentiated from definitive endoderm in vitro,in at least about 15% of the cells differentiated from definitiveendoderm in vitro, in at least about 20% of the cells differentiatedfrom definitive endoderm in vitro, in at least about 25% of the cellsdifferentiated from definitive endoderm in vitro, in at least about 30%of the cells differentiated from definitive endoderm in vitro, in atleast about 35% of the cells differentiated from definitive endoderm invitro, in at least about 40% of the cells differentiated from definitiveendoderm in vitro, in at least about 45% of the cells differentiatedfrom definitive endoderm in vitro, in at least about 50% of the cellsdifferentiated from definitive endoderm in vitro, in at least about 55%of the cells differentiated from definitive endoderm in vitro, in atleast about 60% of the cells differentiated from definitive endoderm invitro, in at least about 65% of the cells differentiated from definitiveendoderm in vitro, in at least about 70% of the cells differentiatedfrom definitive endoderm in vitro, in at least about 75% of the cellsdifferentiated from definitive endoderm in vitro, in at least about 80%of the cells differentiated from definitive endoderm in vitro, in atleast about 85% of the cells differentiated from definitive endoderm invitro, in at least about 90% of the cells differentiated from definitiveendoderm in vitro, in at least about 95% of the cells differentiatedfrom definitive endoderm in vitro or in at least about 98% of the cellsdifferentiated from definitive endoderm in vitro.

In preferred embodiments of the present invention, cell cultures and/orcell populations of mature pancreatic islet hormone-expressing cellscomprise human mature pancreatic islet hormone-expressing cells, thatare non-recombinant cells. In such embodiments, the cell cultures and/orcell populations are devoid of or substantially free of recombinanthuman mature pancreatic islet hormone-expressing cells.

In some embodiments of the present invention, cell cultures and/or cellpopulations comprising mature pancreatic islet hormone-expressing cellsalso include a medium which comprises one or more factors selected fromnicotinamide, exendin 4, HGF and/or IGF1. In some preferred embodiments,the nicotinamide concentration is at least about 10 mM, the exendin 4concentration is at least about 40 ng/ml, the HGF concentration is atleast about 25 ng/ml and the IGF1 concentration is at least about 50ng/ml. In some embodiments, the medium is DMEM.

In certain embodiments of the present invention, cell cultures and/orcell populations comprising mature pancreatic islet hormone-expressingcells also include a medium which comprises one or more secretedhormones selected from ghrelin, insulin, somatostatin and/or glucagon.In other embodiments, the medium comprises C-peptide. In a preferredembodiment, the concentration of one or more secreted hormones orC-peptide in the medium ranges from at least about 1 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA to atleast about 1000 pmol of ghrelin, insulin, somatostatin, glucagon orC-peptide/μg of cellular DNA. In even more preferred embodiments, theconcentration of one or more secreted hormones or C-peptide in themedium is at least about 1 pmol of ghrelin, insulin, somatostatin,glucagon or C-peptide/μg of cellular DNA, at least about 10 pmol ofghrelin, insulin, somatostatin, glucagon or C-peptide/μg of cellularDNA, at least about 25 pmol of ghrelin, insulin, somatostatin, glucagonor C-peptide/μg of cellular DNA, at least about 50 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA, atleast about 75 pmol of ghrelin, insulin, somatostatin, glucagon orC-peptide/μg of cellular DNA, at least about 100 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA, atleast about 150 pmol of ghrelin, insulin, somatostatin, glucagon orC-peptide/μg of cellular DNA, at least about 200 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA, 250pmol of ghrelin, insulin, somatostatin, glucagon or C-peptide/μg ofcellular DNA, at least about 300 pmol of ghrelin, insulin, somatostatin,glucagon or C-peptide/μg of cellular DNA, at least about 350 pmol ofghrelin, insulin, somatostatin, glucagon or C-peptide/μg of cellularDNA, at least about 400 pmol of ghrelin, insulin, somatostatin, glucagonor C-peptide/μg of cellular DNA, at least about 450 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA, atleast about 500 pmol of ghrelin, insulin, somatostatin, glucagon orC-peptide/μg of cellular DNA, at least about 550 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA, atleast about 600 pmol of ghrelin, insulin, somatostatin, glucagon orC-peptide/μg of cellular DNA, 650 pmol of ghrelin, insulin,somatostatin, glucagon or C-peptide/μg of cellular DNA, at least about700 pmol of ghrelin, insulin, somatostatin, glucagon or C-peptide/μg ofcellular DNA, at least about 750 pmol of ghrelin, insulin, somatostatin,glucagon or C-peptide/μg of cellular DNA, at least about 800 pmol ofghrelin, insulin, somatostatin, glucagon or C-peptide/μg of cellularDNA, at least about 850 pmol of ghrelin, insulin, somatostatin, glucagonor C-peptide/μg of cellular DNA, at least about 900 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA, atleast about 950 pmol of ghrelin, insulin, somatostatin, glucagon orC-peptide/μg of cellular DNA or at least about 1000 pmol of ghrelin,insulin, somatostatin, glucagon or C-peptide/μg of cellular DNA.

In some embodiments of the cell cultures and/or cell populationsdescribed herein, the mature pancreatic islet hormone-expressing cellssecrete more than one pancreatic hormone. In other embodiments of thecell cultures and/or cell populations described herein, the maturepancreatic islet hormone-expressing cells secrete a single pancreatichormone. In preferred embodiments, the hormone is insulin. In even morepreferred embodiments, the mature pancreatic islet insulin-expressingcells are responsive to glucose. In other embodiments, human maturepancreatic islet insulin-expressing cells differentiated in vitrosecrete insulin in an amount similar to or greater than the amount ofinsulin secreted by pancreatic beta cells of the human pancreas in vivo.

Using the processes described herein, compositions comprising maturepancreatic islet hormone-expressing cells substantially free of othercell types can be produced. In some embodiments of the presentinvention, the mature pancreatic islet hormone-expressing cellpopulations or cell cultures produced by the methods described hereinare substantially free of cells that significantly express the AFP,SOX7, SOX1, ZIC1 and/or NFM markers.

In one embodiment of the present invention, a description of a maturepancreatic islet insulin-expressing cell based on the expression ofmarkers is NKX6.1 high; NKX2.2 high; INS high; IAPP high; SYP high; GCKhigh; CHGA high; NGN3 low; PAX4 low and MAFB low. For a maturepancreatic islet glucogon-expressing cell, the description based onmarker expression is NKX6.1 high; NKX2.2 high; GLC high; SYP high; GCKhigh; CHGA high; NGN3 low; PAX4 low and MAFB high.

Screening Pancreatic Islet Hormone-Expressing Cells

Certain screening methods described herein relate to methods foridentifying at least one compound that is capable of affecting at leastone pancreatic function of immature and/or mature pancreatic islethormone-expressing cells (together referred to as pancreatic islethormone-expressing cells).

In some embodiments of these screening methods, cell populationscomprising pancreatic islet hormone-expressing cells that have beendifferentiated from pluripotent cells in vitro, such as human pancreaticislet hormone-expressing cells, are obtained. The cell population isthen provided with a candidate compound. At a first time point, which isprior to or at approximately the same time as providing the candidatecompound, the activity of a desired pancreatic function is determined.Alternatively, activity of the desired pancreatic function can bedetermined after providing the candidate compound. At a second timepoint, which is subsequent to the first time point and subsequent to thestep of providing the candidate compound to the cell population,activity of the desired pancreatic function is again determined. Whetherthe candidate compound is capable of affecting at least one pancreaticfunction of the pancreatic islet hormone-expressing cells is determinedby comparing the activity of the desired pancreatic function at thefirst time point with the activity of the desired pancreatic function atthe second time point. If activity of the desired pancreatic function atthe second time point is increased or decreased as compared to activityof the desired pancreatic function at the first time point, then thecandidate compound is capable of affecting the activity of a pancreaticfunction of pancreatic islet hormone-expressing cells.

Some embodiments of the screening methods described herein utilize cellpopulations or cell cultures which comprise human pancreatic islethormone-expressing cells. For example, the cell population can be asubstantially purified population of pancreatic islet hormone-expressingcells. Alternatively, the cell population can be an enriched populationof human pancreatic islet hormone-expressing cells, wherein at leastabout 90%, at least about 91%, at least about 92%, at least about 93%,at least about 94%, at least about 95%, at least about 96%, at leastabout 97% or greater than at least about 97% of the human cells in thecell population are human pancreatic islet hormone-expressing cells. Inother embodiments described herein, the cell population comprises humancells wherein at least about 10%, at least about 15%, at least about20%, at least about 25%, at least about 30%, at least about 35%, atleast about 40%, at least about 45%, at least about 50%, at least about55%, at least about 60%, at least about 65%, at least about 70%, atleast about 75%, at least about 80%, at least about 85% or greater thanat least about 85% of the human cells are human pancreatic islethormone-expressing cells. In some embodiments, the cell populationincludes non-human cells such as non-human feeder cells. In otherembodiments, the cell population includes human feeder cells. In suchembodiments, at least about 10%, at least about 15%, at least about 20%,at least about 25%, at least about 30%, at least about 35%, at leastabout 40%, at least about 45%, at least about 50%, at least about 55%,at least about 60%, at least about 65%, at least about 70%, at leastabout 75%, at least about 80%, at least about 85%, at least about 90%,at least about 95% or greater than at least about 95% of the humancells, other than said feeder cells, are human pancreatic islethormone-expressing cells.

In embodiments of the screening methods described herein, the cellpopulation is contacted or otherwise provided with a candidate (test)compound. The candidate compound can comprise any molecule that may havethe potential to affect the activity of one or more pancreatic functionsof human pancreatic islet hormone-expressing cells. In some embodimentsdescribed herein, the candidate compound comprises a molecule that isknown to be a compound that affects a one or more cellular functions. Inalternate embodiments, the candidate compound comprises a molecule thatis not known to affect any cellular function. In preferred embodiments,the candidate compound comprises a molecule that is not known to affectthe activity of a pancreatic function of human pancreatic islethormone-expressing cells.

In some embodiments of the screening methods described herein, thecandidate compound comprises a small molecule. In preferred embodiments,a small molecule is a molecule having a molecular mass of about 10,000amu or less.

In other embodiments described herein, the candidate compound comprisesa polypeptide. The polypeptide can be any polypeptide including, but notlimited to, a glycoprotein, a lipoprotein, an extracellular matrixprotein, a cytokine, a chemokine, a peptide hormone, an interleukin or agrowth factor.

In some embodiments of the screening methods described herein, thecandidate compound is provided to the cell population in one or moreconcentrations. In some embodiments, the candidate compound is providedto the cell population so that the concentration of the candidatecompound in the medium surrounding the cells ranges from about 0.1 ng/mlto about 10 mg/ml. In some embodiments, the concentration of thecandidate compound in the medium surrounding the cells ranges from about1 ng/ml to about 1 mg/ml. In other embodiments, the concentration of thecandidate compound in the medium surrounding the cells ranges from about10 ng/ml to about 100 μg/ml. In still other embodiments, theconcentration of the candidate compound in the medium surrounding thecells ranges from about 100 ng/ml to about 10 μg/ml. In preferredembodiments, the concentration of the candidate compound in the mediumsurrounding the cells is about 5 ng/ml, about 25 ng/ml, about 50 ng/ml,about 75 ng/ml, about 100 ng/ml, about 125 ng/ml, about 150 ng/ml, about175 ng/ml, about 200 ng/ml, about 225 ng/ml, about 250 ng/ml, about 275ng/ml, about 300 ng/ml, about 325 ng/ml, about 350 ng/ml, about 375ng/ml, about 400 ng/ml, about 425 ng/ml, about 450 ng/ml, about 475ng/ml, about 500 ng/ml, about 525 ng/ml, about 550 ng/ml, about 575ng/ml, about 600 ng/ml, about 625 ng/ml, about 650 ng/ml, about 675ng/ml, about 700 ng/ml, about 725 ng/ml, about 750 ng/ml, about 775ng/ml, about 800 ng/ml, about 825 ng/ml, about 850 ng/ml, about 875ng/ml, about 900 ng/ml, about 925 ng/ml, about 950 ng/ml, about 975ng/ml, about 1 μg/ml, about 2 μg/ml, about 3 μg/ml, about 4 μg/ml, about5 μg/ml, about 6 μg/ml, about 7 μg/ml, about 8 μg/ml, about 9 μg/ml,about 10 μg/ml, about 11 μg/ml, about 12 μg/ml, about 13 μg/ml, about 14μg/ml, about 15 μg/ml, about 16 μg/ml, about 17 μg/ml, about 18 μg/ml,about 19 μg/ml, about 20 μg/ml, about 25 μg/ml, about 50 μg/ml, about 75μg/ml, about 100 μg/ml, about 125 μg/ml, about 150 μg/ml, about 175μg/ml, about 200 μg/ml, about 250 μg/ml, about 300 μg/ml, about 350μg/ml, about 400 μg/ml, about 450 μg/ml, about 500 μg/ml, about 550μg/ml, about 600 μg/ml, about 650 μg/ml, about 700 μg/ml, about 750μg/ml, about 800 μg/ml, about 850 μg/ml, about 900 μg/ml, about 950μg/ml, about 1000 μg/ml or greater than about 1000 μg/ml.

In some embodiments, steps of the screening methods described hereincomprise determining the activity of a desired pancreatic function at afirst time point and a second time point. In some of these embodiments,the first time point can be prior to or at approximately the same timeas providing the cell population with the candidate compound.Alternatively, in some embodiments, the first time point is subsequentto providing the cell population with the candidate compound. In someembodiments, the activities of several pancreatic functions aredetermined at a first time point.

Some preferred pancreatic functions determined in the above embodimentsinclude one or more pancreatic functions selected from the groupconsisting of ghrelin secretion, insulin secretion, glucagon secretionand somatostatin secretion.

In addition to determining the activity of a desired pancreatic functionat a first time point, some embodiments of the screening methodsdescribed herein contemplate determining the activity of the desiredpancreatic function at least one marker at a second time point, which issubsequent to the first time point and which is subsequent to providingthe cell population with the candidate compound. In such embodiments,the activity of the same desired pancreatic function is determined atboth the first and second time points. In some embodiments, theactivities of a plurality of desired pancreatic functions are determinedat both the first and second time points. In such embodiments,activities of the same plurality of pancreatic functions are determinedat both the first and second time points. In some embodiments,activities of a plurality of desired pancreatic functions are determinedat a plurality of time points, each of which is subsequent to the firsttime point, and each of which is subsequent to providing the cellpopulation with the candidate compound. In certain embodiments, theactivity of the desired pancreatic function is determined by Q-PCR. Inother embodiments, the activity of the desired pancreatic function isdetermined by immunocytochemistry.

In certain embodiments of the screening methods described herein, theactivity of the desired pancreatic function determined at the first andsecond time points is an activity of a pancreatic function, such ashormone secretion. In some embodiments, the hormone is insulin, ghrelin,somatostatin or glucagon.

In some embodiments of the screening methods described herein,sufficient time is allowed to pass between providing the cell populationwith the candidate compound and determining the activity of the desiredpancreatic function at the second time point. Sufficient time betweenproviding the cell population with the candidate compound anddetermining the activity of the desired pancreatic function at thesecond time point can be as little as from about 1 hour to as much asabout 10 days. In some embodiments, the activity of the desiredpancreatic function is determined multiple times subsequent to providingthe cell population with the candidate compound. In some embodiments,sufficient time is at least about 1 hour, at least about 6 hours, atleast about 12 hours, at least about 18 hours, at least about 24 hours,at least about 30 hours, at least about 36 hours, at least about 42hours, at least about 48 hours, at least about 54 hours, at least about60 hours, at least about 66 hours, at least about 72 hours, at leastabout 78 hours, at least about 84 hours, at least about 90 hours, atleast about 96 hours, at least about 102 hours, at least about 108hours, at least about 114 hours, at least about 120 hours, at leastabout 126 hours, at least about 132 hours, at least about 138 hours, atleast about 144 hours, at least about 150 hours, at least about 156hours, at least about 162 hours, at least about 168 hours, at leastabout 174 hours, at least about 180 hours, at least about 186 hours, atleast about 192 hours, at least about 198 hours, at least about 204hours, at least about 210 hours, at least about 216 hours, at leastabout 222 hours, at least about 228 hours, at least about 234 hours, atleast about 240 hours, at least about 246 hours, at least about 252hours, at least about 258 hours, at least about 264 hours, or at leastabout 270 hours.

In some embodiments of the methods described herein, it is furtherdetermined whether the activity of the desired pancreatic function atthe second time point has increased or decreased as compared to theactivity of the desired pancreatic function at the first time point. Anincrease or decrease in the activity of the desired pancreatic functionindicates that the candidate compound is capable of affecting theactivity of the desired pancreatic function in the pancreatic islethormone-expressing cells. Similarly, if the activities of a plurality ofpancreatic functions are determined, it is further determined whetherthe activities of the plurality of pancreatic functions at the secondtime point have increased or decreased as compared to the activities ofthe plurality of pancreatic functions at the first time point. Incertain embodiments, wherein the activity of the desired pancreaticfunction is increased at the second time point as compared with thefirst time point, the amount of increase is at least about 2-fold, atleast about 5-fold, at least about 10-fold, at least about 20-fold, atleast about 30-fold, at least about 40-fold, at least about 50-fold, atleast about 60-fold, at least about 70-fold, at least about 80-fold, atleast about 90-fold, at least about 100-fold or more than at least about100-fold. In some embodiments, the amount of increase is less than2-fold. In embodiments where the activity of the desired pancreaticfunction is decreased at the second time point as compared with thefirst time point, the amount of decrease is at least about 2-fold, atleast about 5-fold, at least about 10-fold, at least about 20-fold, atleast about 30-fold, at least about 40-fold, at least about 50-fold, atleast about 60-fold, at least about 70-fold, at least about 80-fold, atleast about 90-fold, at least about 100-fold or more than at least about100-fold. In some embodiments, the amount of decrease is less than2-fold.

Exemplary Factors for Differentiation of hESCs to Pancreatic IsletHormone-Expressing Cells

Table 1 sets out 8 exemplary combinations of factors that can be used toproduce at least some pancreatic islet hormone-expressing cells fromhESC cultures. It will be appreciated that, among other things, theconcentration of each factor used in the differentiation process, thetiming of addition and/or removal of each factor during thedifferentiation process, the concentration of components in thedifferentiation medium, such as serum, during the differentiationprocess will significantly affect the proportion of hESCs that willdifferentiate through the definitive cell lineage and ultimately topancreatic islet hormone-expressing cells.

The leftmost column of Table 1 provides the example number. The next sixcolumns list the factor that may be used to produce or potentiallyenhance the production of the cell type described in the column heading.For example, Table 1 shows that incubating hESCs (stage 0) with a growthfactor of the TGFβ superfamily results in the differentiation of thehESCs to definitive endoderm to definitive endoderm (stage 1). FromTable 1 it can be seen that application of a TGFβ superfamily growthfactor and retinoid at the appropriate times is sufficient to permit theproduction of at least a detectable amount of pancreatic islet hormoneproducing cells from hESCs.

TABLE 1 Definitive Foregut Pancreatic Endocrine Hormone hESCs EndodermEndoderm Endoderm Precursor Expression Number Stage 0 Stage 1 Stage 2Stage 3 Stage 4 Stage 5 1 NF TGFβ NF Ret NF NF 2 NF TGFβ FGF Ret NF NF 3NF TGFβ NF Ret + HI NF NF 4 NF TGFβ + Wnt3a NF Ret NF NF 5 NF TGFβ +Wnt3a FGF + HI Ret + HI + FGF NF NF 6 NF TGFβ + Wnt3a FGF + HI Ret +HI + FGF GSI NF 7 NF TGFβ + Wnt3a FGF + HI Ret + HI + FGF GSI + Ex4 Ex48 NF TGFβ + Wnt3a FGF + HI Ret + HI + FGF GSI + Ex4 Ex4 + HGF + IGFNF—No factor TGFβ—Growth factor of the TGFβ family, preferably activin AFGF—FGF family member, preferably FGF10 and/or FGF7 HI—Hedgehog pathwayinhibitor, preferably KAAD-cyclopamine Ret—Retinoid, preferably retinoicacid (RA) GSI—Gamma secretase inhibitor, preferably DAPT Ex4—Exendin 4HGF—Hepatocyte growth factor IGF—Insulin-like growth factor, preferablyIGF1Reagent-Cell Complexes

Aspects of the present invention relate to compositions, such as cellcultures and/or cell populations, that comprise complexes of one or moreendocrine precursor cells or immature pancreatic islethormone-expressing cells bound to one or more reagents (reagent-cellcomplexes). For example, cell cultures and/or cell populationscomprising reagent-cell complexes, wherein at least about 5% to at leastabout 100% of the endocrine precursor cells in culture are in the formof reagent-cell complexes, can be produced. In other embodiments, cellcultures and/or cell populations can be produced which comprise at leastabout 5%, at least about 10%, at least about 15%, at least about 20%, atleast about 25%, at least about 30%, at least about 35%, at least about40%, at least about 45%, at least about 50%, at least about 55%, atleast about 60%, at least about 65%, at least about 70%, at least about75%, at least about 80%, at least about 85%, at least about 90%, atleast about 95%, at least about 96%, at least about 97%, at least about98%, at least about 99% or at least about 100% reagent-cell complexes.In some embodiments, the reagent cell complexes comprise one or moreendocrine precursor cells bound to one or more antibodies that bind toNCAM. In still other embodiments, the reagent cell complexes compriseone or more endocrine precursor cells bound to one or more ligands thatbind to NCAM, such as NBP10.

Other embodiments provide cell cultures and/or cell populationscomprising reagent-cell complexes, wherein at least about 5% to at leastabout 100% of the immature pancreatic islet hormone-expressing cells inculture are in the form of reagent-cell complexes. In other embodiments,cell cultures and/or cell populations can be produced which comprise atleast about 5%, at least about 10%, at least about 15%, at least about20%, at least about 25%, at least about 30%, at least about 35%, atleast about 40%, at least about 45%, at least about 50%, at least about55%, at least about 60%, at least about 65%, at least about 70%, atleast about 75%, at least about 80%, at least about 85%, at least about90%, at least about 95%, at least about 96%, at least about 97%, atleast about 98%, at least about 99% or at least about 100% reagent-cellcomplexes. In some embodiments, the reagent cell complexes comprise oneor more immature pancreatic islet hormone-expressing cells bound to oneor more antibodies that bind to NCAM. In still other embodiments, thereagent cell complexes comprise one or more immature pancreatic islethormone-expressing cells bound to one or more ligands that bind to NCAM,such as NBP10.

Some embodiments described herein relate to cell cultures and/or cellpopulations comprising from at least about 5% reagent cell complexes toat least about 95% reagent-cell complexes. In some embodiments the cellcultures or cell populations comprise mammalian cells. In preferredembodiments, the cell cultures or cell populations comprise human cells.For example, certain specific embodiments relate to cell culturescomprising human cells, wherein from at least about 5% to at least about95% of the human cells are endocrine precursor cells in the form ofreagent cell complexes. Other embodiments relate to cell culturescomprising human cells, wherein from at least about 5% to at least about95% of the human cells are immature pancreatic islet hormone-expressingcells in the form of reagent cell complexes. Other embodiments relate tocell cultures comprising human cells, wherein at least about 5%, atleast about 10%, at least about 15%, at least about 20%, at least about25%, at least about 30%, at least about 35%, at least about 40%, atleast about 45%, at least about 50%, at least about 55%, at least about60%, at least about 65%, at least about 70%, at least about 75%, atleast about 80%, at least about 85%, at least about 90% or greater than90% of the human cells are reagent cell complexes. In embodiments wherethe cell cultures or cell populations comprise human feeder cells, theabove percentages are calculated without respect to the human feedercells in the cell cultures or cell populations. In some embodiments, thereagent cell complexes comprise one or more endocrine precursor cells orimmature pancreatic islet hormone-expressing cells bound to NCAM or SYP.

In some embodiments, the expression of NGN3, PAX4, and/or NKX2.2 isenhanced in the endocrine precursor cells present in the reagent-cellcomplexes that have been described above compared to the expression ofAFP, SOX7, SOX1, ZIC1, NFM, SYP, SST, GHRL, PAX6, MAFA, INS, GCG, and/orCHGA. In preferred embodiments, the endocrine precursor cells expressingNGN3, NKX2.2 and/or PAX4 do not express significant levels or amounts ofAFP, SOX7, SOX1, ZIC1, NFM, SYP, SST, GHRL, PAX6, MAFA, INS, GCG and/orCHGA.

In some embodiments, the expression of MAFB is enhanced in the immaturepancreatic islet hormone-expressing cells present in the reagent-cellcomplexes that have been described above compared to the expression ofAFP, SOX7, SOX1, ZIC1, NFM, NGN3 and/or MAFA. In preferred embodiments,the immature pancreatic islet hormone-expressing cells expressing MAFBdo not express significant levels or amounts of AFP, SOX7, SOX1, ZIC1,NFM, NGN3 and/or MAFA.

Additional embodiments described herein relate to compositions, such ascell cultures and/or cell populations that comprise both pluripotentcells, such as stem cells, and reagent-cell complexes. In someembodiments, the compositions also comprise multipotent cells, such asdefinitive endoderm cells, foregut endoderm cells, PDX1-positivepancreatic endoderm cells. For example, using the methods describedherein, compositions comprising mixtures of hESCs and/or definitiveendoderm cells and reagent-cell complexes of endocrine precursor cellscan be produced. Further, using the methods described herein,compositions comprising mixtures of hESCs, definitive endoderm cells,foregut endoderm cells, and/or PDX1-positive pancreatic endoderm cells,and reagent-cell complexes of endocrine precursor cells and/orreagent-cell complexes of immature pancreatic islet hormone-expressingcells can be produced. In some embodiments, compositions comprising atleast about 5 reagent-cell complexes for about every 95 pluripotent,definitive endoderm cells, foregut endoderm cells, and/or PDX1-positivepancreatic endoderm cells, are provided. In other embodiments,compositions comprising at least about 95 reagent-cell complexes forabout every 5 pluripotent cells, definitive endoderm cells, foregutendoderm cells, and/or PDX1-positive pancreatic endoderm cells areprovided. Additionally, compositions comprising other ratios ofreagent-cell complexes cells to pluripotent, definitive endoderm cells,foregut endoderm cells, and/or PDX1-positive pancreatic endoderm cellsare contemplated. For example, compositions comprising at least about 1reagent-cell complex for about every 1,000,000 pluripotent, definitiveendoderm cells, foregut endoderm cells, and/or PDX1-positive pancreaticendoderm cells, at least about 1 reagent-cell complex for about every100,000 pluripotent, definitive endoderm cells, foregut endoderm cells,and/or PDX1-positive pancreatic endoderm cells, at least about 1reagent-cell complex cell for about every 10,000 pluripotent, definitiveendoderm cells, foregut endoderm cells, and/or PDX1-positive pancreaticendoderm cells, at least about 1 reagent-cell complex for about every1000 pluripotent, definitive endoderm cells, foregut endoderm cells,and/or PDX1-positive pancreatic endoderm cells, at least about 1reagent-cell complex for about every 500 pluripotent, definitiveendoderm cells, foregut endoderm cells, and/or PDX1-positive pancreaticendoderm cells, at least about 1 reagent-cell complex for about every100 pluripotent, definitive endoderm cells, foregut endoderm cells,and/or PDX1-positive pancreatic endoderm cells, at least about 1reagent-cell complex for about every 10 pluripotent, definitive endodermcells, foregut endoderm cells, and/or PDX1-positive pancreatic endodermcells, at least about 1 reagent-cell complex for about every 5pluripotent, definitive endoderm cells, foregut endoderm cells, and/orPDX1-positive pancreatic endoderm cells, at least about 1 reagent-cellcomplex for about every 2 pluripotent, definitive endoderm cells,foregut endoderm cells, and/or PDX1-positive pancreatic endoderm cells,at least about reagent-cell complexes for about every 1 pluripotent,definitive endoderm cell, foregut endoderm cell, and/or PDX1-positivepancreatic endoderm cell, at least about 5 reagent-cell complexes forabout every 1 pluripotent, definitive endoderm cell, foregut endodermcell, and/or PDX1-positive pancreatic endoderm cell, at least about 10definitive endoderm cells for about every 1 pluripotent, definitiveendoderm cell, foregut endoderm cell, and/or PDX1-positive pancreaticendoderm cell, at least about 20 reagent-cell complexes for about every1 pluripotent, definitive endoderm cell, foregut endoderm cell, and/orPDX1-positive pancreatic endoderm cell, at least about 50 reagent-cellcomplexes for about every 1 pluripotent, definitive endoderm cell,foregut endoderm cell, and/or PDX1-positive pancreatic endoderm cell, atleast about reagent-cell complexes for about every 1 pluripotent,definitive endoderm cell, foregut endoderm cell, and/or PDX1-positivepancreatic endoderm cell, at least about 1000 reagent-cell complexes forabout every 1 pluripotent, definitive endoderm cell, foregut endodermcell, and/or PDX1-positive pancreatic endoderm cell, at least about10,000 reagent-cell complexes for about every 1 pluripotent, definitiveendoderm cell, foregut endoderm cell, and/or PDX1-positive pancreaticendoderm cell, at least about 100,000 reagent-cell complexes for aboutevery 1 pluripotent, definitive endoderm cell, foregut endoderm cell,and/or PDX1-positive pancreatic endoderm cell; and at least about1,000,000 reagent-cell complexes for about every 1 pluripotent,definitive endoderm cell, foregut endoderm cell, and/or PDX1-positivepancreatic endoderm cell are contemplated. In some embodiments of thepresent invention, the pluripotent cells are human pluripotent stemcells. In certain embodiments the stem cells are derived from a morula,the inner cell mass of an embryo or the gonadal ridges of an embryo. Incertain other embodiments, the pluripotent cells are derived from thegonadal or germ tissues of a multicellular structure that has developedpast the embryonic stage.

Method of Producing Pancreatic Hormone-Expressing Cells Using Noggin

Methods for differentiating pancreatic hormone-expressing cells fromless differentiated cell types have been described above. These methodscan be enhanced by the addition of noggin to the differentiation mediumat the appropriate stage of differentiation. In some embodiments, noggincan facilitate differentiation of foregut endoderm cells without theaddition of supplemental retinoid. However, when noggin is used incombination with a retinoid, the production of pancreatichormone-expressing cells is generally increased. Specific protocolswhich describe the use of noggin in the differentiation of hESC cells topancreatic hormone-expressing cells are described in Examples 18 and 19below. The following paragraphs provide a general description of hownoggin can be used in the differentiation process. It should beappreciated that the disclosure below incorporates methods already fullydescribed above and in the US patent applications that have beenincorporated into this document by reference. As such, the disclosure ofmethod steps already previously described apply to the paragraphs thatfollow.

Some embodiments of the present invention include a method of producinghuman pancreatic hormone-expressing cells comprising the steps ofproviding a population of pluripotent human embryonic stem cells (hESCs)with at least one growth factor of the TGF-β superfamily to obtain humandefinitive endoderm cells, providing the population of human definitiveendoderm cells with at least one fibroblast growth factor to obtainhuman foregut endoderm cells and then providing the population of humanforegut endoderm cells with noggin to obtain human endocrine precursorcells, which are then incubated for a sufficient time to permit humanpancreatic islet hormone-expressing cells to form. In some embodiment, asufficient time for human pancreatic hormone-expressing cells to formhas been determined by detecting the presence of human pancreatichormone-expressing cells in the cell population. As described above,human pancreatic hormone-expressing cells can be characterized bycertain marker expression. Accordingly, methods of detecting such markerexpression, such as Q-PCR or immunocytochemistry can be used todetermine the about of time that is sufficient to permit pancreatichormone-expressing cell formation. In some embodiments, one or moremarkers selected from the group consisting of pancreatic duodenalhomeobox 1 (PDX1), ghrelin (GHRL), islet amyloid polypeptide (IAPP),insulin (INS), pancreatic polypeptide (PP), ISL1 transcription factor(ISL1), NKX6 transcription factor related locus 1 (NKX6.1), paired box 6(PAX6), and pancreas specific transcription factor 1a (PTF1a) aredetected.

In some embodiments of the above-described method, from at least about2% to at least about 95% of the human cells in the cell populationdifferentiate into human pancreatic hormone-expressing cells. In someembodiments, at least about 2%, at least about 5%, at least about 10%,at least about 15%, at least about 20%, at least about 25%, at leastabout 30%, at least about 35%, at least about 40%, at least about 45%,at least about 50%, at least about 55%, at least about 60%, at leastabout 65%, at least about 70%, at least about 75%, at least about 80%,at least about 85%, at least about 90%, at least about 95% or greaterthan about 95% of the human cells in the cell population differentiateinto human pancreatic hormone-expressing cells.

In some embodiments of the above-described methods, the differentiatingcell population with a gamma secretase inhibitor, such as DAPT. Incertain embodiments, the gamma secretase inhibitor is provided to thecell population at about the same time as providing noggin or afterproviding noggin. In some embodiments, the gamma secretase inhibitor isprovided just prior to providing noggin. For example, the gammasecretase inhibitor can be provided from about 3 days prior to about 7days subsequent to the addition of noggin. In a preferred embodiment,the gamma secretase inhibitor is provided about 1 day to about 4 dayssubsequent to providing noggin to the cell culture or cell population.In a more preferred embodiment, the gamma secretase inhibitor isprovided about 3 days subsequent to providing noggin to the cell cultureor cell population. In some embodiments of the present invention, thegamma secretase inhibitor is provided to the cell population at aconcentration ranging from about 0.1 μM to about 10 μM. In a preferredembodiment, the gamma secretase inhibitor is provided to the cellpopulation at a concentration of about 1 μM.

In other embodiments of the above-described method, the at least onefibroblast growth factor is selected from FGF-10, FGF-22 or FGF-7 (KGF).In a preferred embodiment, the fibroblast growth factor that is providedis KGF. In such embodiments, KGF is provided to the cell culture at aconcentration ranging from about 1 ng/ml to about 1000 ng/ml. In someembodiments, KGF can be provided to the differentiating cell culture ata concentration of at least about 1 ng/ml, at least about 2 ng/ml, atleast about 5 ng/ml, at least about 10 ng/ml, at least about 15 ng/ml,at least about 20 ng/ml, at least about 25 ng/ml, at least about 30ng/ml, at least about 35 ng/ml, at least about 40 ng/ml, at least about45 ng/ml, at least about 50 ng/ml, at least about 55 ng/ml, at leastabout 60 ng/ml, at least about 65 ng/ml, at least about 70 ng/ml, atleast about 75 ng/ml, at least about 80 ng/ml, at least about 85 ng/ml,at least about 90 ng/ml, at least about 95 ng/ml, at least about 100ng/ml, at least about 110 ng/ml, at least about 120 ng/ml, at leastabout 130 ng/ml, at least about 140 ng/ml, at least about 150 ng/ml, atleast about 160 ng/ml, at least about 170 ng/ml, at least about 180ng/ml, at least about 190 ng/ml, at least about 200 ng/ml, at leastabout 250 ng/ml, at least about 300 ng/ml, at least about 350 ng/ml, atleast about 400 ng/ml, at least about 450 ng/ml, at least about 500ng/ml, at least about 750 ng/ml, or at least about 1000 ng/ml. In someembodiments of the above-described method, the at least one fibroblastgrowth factor comprises any fibroblast growth factor or a ligand thatstimulates or otherwise interacts with the fibroblast growth factor 2receptor Mb (FGFR2(IIIb).

In still other embodiments of the above-described method, a hedgehoginhibitor is provided to the differentiating cell population at aboutthe same time as adding the at least one fibroblast growth factor. Insome embodiments, the hedgehog inhibitor is provided just prior toproviding the fibroblast growth factor. For example, the hedgehoginhibitor can be provided from about 2 days prior to about 3 dayssubsequent to the addition of the fibroblast growth factor. In apreferred embodiment, the hedgehog inhibitor is provided at about thesame time as providing the fibroblast growth factor to the cell cultureor cell population. In a preferred embodiment, the hedgehog inhibitor isKAAD-cyclopamine.

In a preferred embodiment, the hedgehog inhibitor is provided to thecell culture at a concentration ranging from about 0.01 μM to about 10μM. In some embodiments, the hedgehog inhibitor can be provided at aconcentration of at least about 0.01 μM, at least about 0.02 μM, atleast about 0.04 μM, at least about 0.08 μM, at least about 0.1 μM, atleast about 0.2 μM, at least about 0.3 μM, at least about 0.4 μM, atleast about 0.5 μM, at least about 0.6 μM, at least about 0.7 μM, atleast about 0.8 μM, at least about 0.9 μM, at least about 1 μM, at leastabout 1.1 μM, at least about 1.2 μM, at least about 1.3 μM, at leastabout 1.4 μM, at least about 1.5 μM, at least about 1.6 μM, at leastabout 1.7 μM, at least about 1.8 μM, at least about 1.9 μM, at leastabout 2 μM, at least about 2.1 μM, at least about 2:2 μM, at least about2.3 μM, at least about 2.4 μM, at least about 2.5 μM, at least about 2.6μM, at least about 2.7 μM, at least about 2.8 μM, at least about 2.9 μM,at least about 3 μM, at least about 3.5 μM, at least about 4 μM, atleast about 4.5 μM, at least about 5 μM, at least about 10 μM, at leastabout 20 μM, at least about 30 μM, at least about 40 μM or at leastabout 50 μM.

In the step of differentiating hESCs to definitive endoderm cells, agrowth factor of the TGF-β superfamily is provided to the cellpopulation. In some embodiments, the TGF-β superfamily is selected fromthe group consisting of Nodal, activin A, activin B and combinationsthereof. In a preferred embodiment, the TGF-β superfamily comprisesactivin A. In some embodiments, the activin A is provided to said hESCsat a concentration ranging from about 10 ng/ml to about 1000 ng/ml. Insome embodiments, activin A is provided to the cell population at aconcentration of at least about 1 ng/ml, at least about 5 ng/ml, atleast about 10 ng/ml, at least about 25 ng/ml, at least about 50 ng/ml,at least about 75 ng/ml, at least about 100 ng/ml, at least about 200ng/ml, at least about 300 ng/ml, at least about 400 ng/ml, at leastabout 500 ng/ml, or at least about 1000 ng/ml.

In some embodiments, of the above-described methods the hESCs are alsoprovided with wingless-type MMTV integration site family member 3A(Wnt3A). In a preferred embodiment, Wnt3A is provided at a concentrationranging from about 1 ng/ml to about 1000 ng/ml. In some embodiments,Wnt3A is provided to the cell population at a concentration of at leastabout 1 ng/ml, at least about 5 ng/ml, at least about 10 ng/ml, at leastabout 25 ng/ml, at least about 50 ng/ml, at least about 75 ng/ml, atleast about 100 ng/ml, at least about 200 ng/ml, at least about 300ng/ml, at least about 400 ng/ml, at least about 500 ng/ml, or at leastabout 1000 ng/ml.

Some embodiments of the above-described methods comprise withdrawing anygrowth factor of the TGF-β superfamily that may be present in saidpopulation of definitive endoderm cells. In such embodiments, the TGF-βsuperfamily growth factor is TGF-β superfamily growth factor that hasbeen exogenously provided to the cell culture. That is, the TGF-βsuperfamily growth factor that is withdrawn is not TGF-β superfamilygrowth factor that is present as a basal component of the medium asformulated by those of ordinary skill in the art.

Additional embodiments of the above-described methods further compriseproviding a retinoid to the cell population at about the same time orafter providing at least one fibroblast growth factor. In certainembodiments, the retinoid is provided to the cell population at aboutthe same time as providing at least one fibroblast growth factor orafter providing at least one fibroblast growth factor. In someembodiments, the retinoid is provided just prior to providing at leastone fibroblast growth factor. In other embodiments, the retinoid isprovided to the cell population at about the same time as providingnoggin. For example, the retinoid can be provided from about 3 daysprior to about 7 days subsequent to the addition of at least onefibroblast growth factor. In a preferred embodiment, the retinoid isprovided about 1 day to about 4 days subsequent to providing at leastone fibroblast growth factor to the cell culture or cell population. Ina more preferred embodiment, the retinoid is provided about 3 dayssubsequent to providing at least one fibroblast growth factor to thecell culture or cell population.

In some embodiments, of the above-described methods the retinoid isprovided to the differentiating cell population at a concentrationranging from about 0.01 μM to about 100 μM. In some embodiments, theretinoid is provided at a concentration at a concentration of at leastabout 1 nM, at least about 0.01 μM, at least about 0.02 μM, at leastabout 0.04 μM, at least about 0.08 μM, at least about 0.1 μM, at leastabout 0.2 μM, at least about 0.3 μM, at least about 0.4 μM, at leastabout 0.5 μM, at least about 0.6 μM, at least about 0.7 μM, at leastabout 0.8 μM, at least about 0.9 μM, at least about 1 μM, at least about1.1 μM, at least about 1.2 μM, at least about 1.3 μM, at least about 1.4μM, at least about 1.5 μM, at least about 1.6 μM, at least about 1.7 μM,at least about 1.8 μM, at least about 1.9 μM, at least about 2 μM, atleast about 2.1 μM, at least about 2.2 μM, at least about 2.3 μM, atleast about 2.4 μM, at least about 2.5 μM, at least about 2.6 μM, atleast about 2.7 μM, at least about 2.8 μM, at least about 2.9 μM, atleast about 3 μM, at least about 3.5 μM, at least about 4 μM, at leastabout 4.5 μM, at least about 5 μM, at least about 10 μM, at least about20 μM, at least about 30 μM, at least about 40 μM, at least about 50 μM,at least about 75 μM or at least about 100 μM. I a preferred embodiment,the retinoid is retinol. In such embodiment, the retinol can be thatincluded in B27 supplement. In more preferred embodiments, the retinoidis retinoic acid.

In some embodiments of the methods described above, the hESCs aredifferentiated to human definitive endoderm cells in a medium comprisingless than about 2% serum. For example, in some differentiationprocesses, the serum concentration of the medium can be less than about0.05% (v/v), less than about 0.1% (v/v), less than about 0.2% (v/v),less than about 0.3% (v/v), less than about 0.4% (v/v), less than about0.5% (v/v), less than about 0.6% (v/v), less than about 0.7% (v/v), lessthan about 0.8% (v/v), less than about 0.9% (v/v), less than about 1%(v/v) or less than about 2% (v/v). In some embodiments, differentiationis initiated in the absence of serum and in the absence of insulinand/or insulin-like growth factor. During the course of differentiation,the serum concentration may be gradually increased in order to promoteadequate cell survival. In preferred embodiments, differentiation ofhESCs to definitive endoderm cells is initiated in the absence of serumand in the absence of any supplement comprising insulin or insulin-likegrowth factors. The absence of serum and absence of supplementcomprising insulin or insulin-like growth factors is maintained forabout 1 to about 2 days, after which, serum is gradually added to thedifferentiating cell culture over the course of differentiation. Inpreferred embodiments, the concentration of serum does not exceed about2% during the course of differentiation.

With respect to the above-described method, the hESCs can be derivedfrom a tissue selected from the group consisting of the morula, the ICMof an embryo and the gonadal ridges of an embryo. In preferredembodiments, the hESCs are derived from a preimplantation embryo.

Differentiation of hESCs to Endocrine Precursor Cells and PancreaticHormone-Expressing Cells without the Use of Histone DeacetylaseInhibitors

Some embodiments of the invention included herein relate to in vitrocell cultures and in vitro cell populations as set forth herein thathave not been cultured and/or differentiated in the presence of asubstantial amount of sodium butyrate or other histone deacetylaseinhibitor for a substantial length of time during any stage of theirdevelopment. With respect to culturing and/or differentiating cells inthe presence of sodium butyrate or other histone deacetylase inhibitor,“substantial amount” means any amount sufficient to allow the sodiumbutyrate or other histone deacetylase inhibitor to mediate inhibitoryeffects on histone deacetylase in approximately half of the human cellsin the cell culture or cell population. With respect to culturing and/ordifferentiating cells in the presence of sodium butyrate or otherhistone deacetylase inhibitor, “substantial length of time” means anylength of time sufficient to allow the sodium butyrate or other histonedeacetylase inhibitor to mediate inhibitory effects on histonedeacetylase in approximately half of the human cells in the cell cultureor cell population. Accordingly, both the concentration of sodiumbutyrate or other histone deacetylase inhibitor and the time that it ispresent in the cell culture will influence the extent of the inhibitoryeffect. For example, a substantial amount can range from about 1 nM toabout 100 mM. In some embodiments, a substantial amount is about 1 nM,about 2 nM, about 5 nM, about 10 nM, about 20 nM, about 30 nM, about 40nM, about 50 nM, about 75 nM, about 100 nM, about 250 nM, about 500 nM,about 750 nM, about 1 μM, about 10 μM, about 25 μM, about 50 μM, about75 μM, about 100 μM, about 250 μM, about 500 μM, about 750 μM, about 1mM, about 10 mM, about 25 mM, about 50 mM, about 75 mM, about 100 mM orgreater than about 100 mM. In some embodiments, a substantial length oftime can be about 10 minutes, about 30 minutes, about 1 hour, about 2hours, about 4 hours, about 8 hours, about 12 hours, about 16 hours,about 1 day, about 2 days, about 3 days, about 4 day, about 5 days orgreater than about 5 days. For example, cell types that have not beencultured and/or differentiated in the presence of sodium butyrate oranother histone deacetylase inhibitor include hESCs, human definitiveendoderm cells, human foregut endoderm cells, human PDX1-positiveforegut endoderm cells, human endocrine precursor cells, human immaturepancreatic hormone-expressing cells and mature pancreatichormone-expressing cells. In some embodiments of the present invention,in vitro cell cultures and in vitro cell populations as set forth hereinare cultured and/or differentiated in the complete absence of sodiumbutyrate or other histone deacetylase inhibitor at one or more timesduring the stages of their development.

Additional embodiments described herein include methods of producing oneor more of the above-described cell cultures or cell populations in theabsence of a substantial amount of sodium butyrate or other histonedeacetylase inhibitor. In such embodiments, no substantial amount ofexogenous sodium butyrate or other histone deacetylase inhibitor issupplied to the cells of the cell culture or cell population for anysubstantial length of time during any stage of the differentiationprocess. As indicated above, “substantial amount” means any amount ofsodium butyrate or other histone deacetylase inhibitor sufficient tomediate inhibitory effects on histone deacetylase in approximately halfof the human cells in the cell culture or cell population. Also asindicated above, “substantial length of time” means any length of timesufficient to allow the sodium butyrate or other histone deacetylaseinhibitor to mediate inhibitory effects on histone deacetylase inapproximately half of the human cells in the cell culture or cellpopulation. In certain embodiments, differentiation methods describedherein include differentiating hESCs, human definitive endoderm cells,human foregut endoderm cells, human PDX1-positive foregut endodermcells, human endocrine precursor cells, human immature pancreatichormone-expressing cells and mature pancreatic hormone-expressing cellsin the absence of a substantial amount of sodium butyrate or otherhistone deacetylase inhibitor. In some embodiments of the presentinvention, hESCs, human definitive endoderm cells, human foregutendoderm cells, human PDX1-positive foregut endoderm cells, humanendocrine precursor cells, human immature pancreatic hormone-expressingcells and mature pancreatic hormone-expressing cells are cultured and/ordifferentiated in the complete absence of sodium butyrate or otherhistone deacetylase inhibitor.

Differentiation of non-recombinant hESCs to Endocrine Precursor Cellsand Pancreatic Hormone-Expressing Cells

Additional embodiments of the present invention relate non-recombinantcell cultures and non-recombinant cell populations comprising one ormore cell types selected from hESCs, human definitive endoderm cells,human foregut endoderm cells, human PDX1-positive foregut endodermcells, human endocrine precursor cells, human immature pancreatichormone-expressing cells and mature pancreatic hormone-expressing cells.In some embodiments of the non-recombinant cell cultures andnon-recombinant cell populations at least one of the cell types is anon-recombinant cell type. In preferred embodiments, all the cell typesin the cell culture or cell population are non-recombinant cell types.By “non-recombinant” is meant that the cell are not engineered toexpress the product of one or more exogenous genes or the product of afunctional portion of one or more exogenous genes, especially anexogenous marker gene, which includes, but is not limited to, exogenousmarker genes that can be used for selection and/or screening. Specificexamples of exogenous marker genes include, but are not limited to,genes encoding green fluorescent protein (GFP), enhanced greenfluorescent protein (EGFP), luciferase and any other marker useful forcell sorting. Other exemplary exogenous marker genes include antibioticresistance genes. In some embodiments, non-recombinant cells includecells that have not been engineered to contain an exogenous or foreigngene. In some embodiments, the cells cultures and cell populationsdescribed herein are karyotypically normal.

Further embodiments of the present invention relate to methods ofproducing non-recombinant cell cultures and non-recombinant cellpopulations comprising one or more cell types selected from hESCs, humandefinitive endoderm cells, human foregut endoderm cells, humanPDX1-positive foregut endoderm cells, human endocrine precursor cells,human immature pancreatic hormone-expressing cells and mature pancreatichormone-expressing cells. In such embodiments, one or more cell types inthe cell culture or cell population are non-recombinant cell types. In apreferred embodiment, all of the cell types in the cell culture or cellpopulation are non-recombinant cell types. In especially preferredembodiments of the methods described herein, non-recombinant hESCs aredifferentiated to definitive endoderm cells and further intohormone-expressing cells, thereby producing non-recombinanthormone-expressing cells. In certain embodiments, the methods describedherein do not include a step of sorting cells based on the expression ornonexpression of an exogenous or foreign marker gene product. Examplesof products of marker genes are green fluorescent protein (GFP),enhanced green fluorescent protein (EGFP), luciferase and any othermarker useful for cell sorting. In some embodiments, non-recombinantcells in the cell cultures or cell populations, which have not beenengineered to contain a gene encoding an exogenous or foreign markerprotein, are differentiated to definitive endoderm cells and furtherinto hormone-expressing cells. In some embodiments, non-recombinantcells include cells that have not been engineered to contain anexogenous or foreign gene. In some embodiments, karyotypically normalcells are differentiated to definitive endoderm cells and further intohormone-expressing cells, thereby producing non-recombinanthormone-expressing cells.

Having generally described this invention, a further understanding canbe obtained by reference to certain specific examples which are providedherein for purposes of illustration only, and are not intended to belimiting.

EXAMPLES

Many of the examples below describe the use of pluripotent human cells.Methods of producing pluripotent human cells are well known in the artand have been described numerous scientific publications, including U.S.Pat. Nos. 5,453,357, 5,670,372, 5,690,926, 6,090,622, 6,200,806 and6,251,671 as well as U.S. Patent Application Publication No.2004/0229350, the disclosures of which are incorporated herein byreference in their entireties.

Example 1 Human ES Cells

For our studies of pancreatic islet hormone-expressing cell development,we employed human embryonic stem cells, which are pluripotent and candivide seemingly indefinitely in culture while maintaining a normalkaryotype. ES cells were derived from the 5-day-old embryo inner cellmass using either immunological or mechanical methods for isolation. Inparticular, the human embryonic stem cell line hESCyt-25 was derivedfrom a supernumerary frozen embryo from an in vitro fertilization cyclefollowing informed consent by the patient. Upon thawing the hatchedblastocyst was plated on mouse embryonic fibroblasts (MEF), in ES medium((DMEM, 20% FBS, non essential amino acids, beta-mercaptoethanol, andFGF2). The embryo adhered to the culture dish and after approximatelytwo weeks, regions of undifferentiated hESCs were transferred to newdishes with MEFs. Transfer was accomplished with mechanical cutting anda brief digestion with dispase, followed by mechanical removal of thecell clusters, washing and re-plating. Since derivation, hESCyt-25 hasbeen serially passaged over 100 times. We employed the hESCyt-25 humanembryonic stem cell line as our starting material for the production ofendocrine precursor cells, and subsequently, pancreatic islethormone-expressing cells. Additionally, we have used other hESC linesdeveloped both by us and by others including, but not limited to,Cyt-49, Cyt-203, BG01, BG02 and BG03.

It will be appreciated by those of skill in the art that stem cells orother pluripotent cells can also be used as starting material for thedifferentiation procedures described herein. For example, cells obtainedfrom embryonic gonadal ridges, which can be isolated by methods known inthe art, can be used as pluripotent cellular starting material.

Example 2 hESCyt-25 Characterization

The human embryonic stem cell line, hESCyt-25 has maintained a normalmorphology, karyotype, growth and self-renewal properties over 18 monthsin culture. This cell line displays strong immunoreactivity for theOCT4, SSEA-4 and TRA-1-60 antigens, all of which are characteristic ofundifferentiated hESCs and displays alkaline phosphatase activity aswell as a morphology identical to other established hESC lines.Furthermore, the human stem cell line, hESCyt-25, also readily formsembryoid bodies (EBs) when cultured in suspension. As a demonstration ofits pluripotent nature, hESCyT-25 differentiates into various cell typesthat represent the three principal germ layers. Ectoderm production wasdemonstrated by Q-PCR for ZIC1 as well as immunocytochemistry (ICC) fornestin and more mature neuronal markers. Immunocytochemical staining forβ-III tubulin was observed in clusters of elongated cells,characteristic of early neurons. Previously, we treated EBs insuspension with retinoic acid, to induce differentiation of pluripotentstem cells to visceral endoderm (VE), an extra-embryonic lineage.Treated cells expressed high levels of α-fetoprotein (AFP) and SOX7, twomarkers of VE, by 54 hours of treatment. Cells differentiated inmonolayer expressed AFP in sporadic patches as demonstrated byimmunocytochemical staining. As will be described below, the hESCyT-25cell line was also capable of forming definitive endoderm, as validatedby real-time quantitative polymerase chain reaction (Q-PCR) andimmunocytochemistry for SOX17, in the absence of AFP expression. Todemonstrate differentiation to mesoderm, differentiating EBs wereanalyzed for Brachyury gene expression at several time points. Brachyuryexpression increased progressively over the course of the experiment. Inview of the foregoing, the hESCyT-25 line is pluripotent as shown by theability to form cells representing the three germ layers.

Example 3 Definitive Endoderm Cells as Intermediates in the Productionof Cells Expressing Pancreatic Hormones

Human embryonic stem cells were differentiated for 21 days via a 4-stepprotocol to achieve islet hormone-expressing cells. Three differentconditions were used for the first step after which all plates receivedthe identical treatment. The first step comprised 5 days differentiationunder one of the following conditions: i) activin A (100 ng/ml) torobustly produce DE (D'Amour, K., et al., Nature Biotechnology 23,1534-1541, (2005)), ii) 2% FBS with no exogenous growth factors, therebyproducing mesoderm and extraembryonic endoderm, or iii) follistatin (50ng/ml) and noggin (100 ng/ml), thereby producing neural ectoderm. Step 2comprised 3 days differentiation in RPMI with 2% FBS containing FGF10(50 ng/mL) and KAAD-cyclopamine (1 μM). Step 3 comprised 5 daysdifferentiation in CMRL with B27 supplement (1:100) containing FGF10 (50ng/mL), KAAD-cyclopamine (1 μM), retinoic acid (2 μM), and DAPT (1 μM).The fourth step consisted of 8 days differentiation in DMEM with B27supplement (1:100) containing nicotinamide (10 mM), exendin 4 (40ng/mL), hepatocyte growth factor (HGF-25 ng/mL), and insulin-like growthfactor (IGF)-1 (50 ng/mL). Duplicate samples were taken from each plateat multiple time points and gene expression was analyzed by real-timequantitative PCR.

As shown in FIGS. 2A-F, at 5 days of differentiation, the activin Atreatment yielded robust production of definitive endoderm (DE) asindicated by elevated expression of SOX17 and CXCR4. The relativeabsence of expression for SOX17 and CXCR4 in the no factor (2NF) and thefollistatin/noggin treatments indicated that little or no DE wasproduced under these conditions. Conversely, the no factor treatmentinduced robust expression of SOX7, a marker of extraembryonic endoderm,and ISL1, which is expressed in various mesoderm populations. Treatmentwith follistatin and noggin induced robust expression of SOX1 and PAX6,which indicated robust differentiation to neural ectoderm. As shown inFIGS. 2G-N, we found that the expression of the pancreatic endodermmarker PDX1 as well as the pancreatic endocrine transcription factors(NGN3, NKX2.2, NKX6.1) and endocrine hormones occur subsequent to theproduction of DE. Efficient production of these cells correlates withthe efficient production of DE. When extraembryonic endoderm/mesoderm orearly neural ectoderm lineages are induced instead of DE, the pancreaticendoderm or pancreatic endocrine markers are not appreciably expressedin those cells after treatment with the identical culture conditionsthat produce islet hormone gene expression when applied to culturesenriched in DE. However, pre-specification of hESCs to DE is sufficientto achieve the mature pancreatic phenotypes characterized by theexpression of PDX1, NGN3, insulin, and glucagon.

Example 4 Insulin/IGF Signaling Promotes Translation of PDX1 Protein

Human embryonic stem cells were differentiated in RPMI medium containingactivin A (100 ng/ml) for 5 days. The FBS concentrations changed from 0%for the first 24 hours followed by 0.2% for the next 24 hrs and then to2% for the remaining 3 days. During the next 4 days, the plates weresubjected to different media conditions. They were either incubated ini) RPMI with 2% FBS and activin A (100 ng/ml), ii) RPMI with 2% FBS,activin A (25 ng/ml) and retinoic acid, iii) CMRL with 0.2% FBS and B27supplement (1:100), activin A (25 ng/ml) and retinoic acid, and iv) CMRLwith 0.2% FBS and B27 supplement (1:100), activin A (25 ng/ml), retinoicacid and exendin (40 ng/ml). The concentration of retinoic acid changedfrom 2 μM for 48 hours followed by 1 μM for 24 hours to 0.2 μM for thelast 24 hours. The cells were harvested for protein and mRNA analyses ondays 7, 8 and 9.

Another factor that promotes the expression of PDX1 protein is insulin(e.g., concentrations from about 0.2-20 μg/ml) or insulin-like growthfactor (e.g., concentrations from about 10-500 ng/ml). Withoutsufficient insulin signaling, PDX1 mRNA was expressed withoutsignificant translation into PDX1 protein (FIGS. 4A-B). The base mediumcan be RPMI, CMRL, OptiMEM or DMEM with or without 2% FBS. If the basemedium is supplemented with sufficient insulin/IGF and FGF10, PDX1protein will be expressed.

Example 5 Retinoic Acid Promotes the Differentiation of hESCs to thePancreatic Insulin Expressing Phenotype

Human embryonic stem cells were differentiated for 17 days via a 4-stepprotocol to achieve islet hormone-expressing cells. The first stepcomprised 5 days differentiation in activin A (100 ng/mL) to robustlyproduce DE (D'Amour, K., et al., Nature Biotechnology 23, 1534-1541,(2005)). Step 2 comprised 2 days differentiation in RPMI with 2% FBScontaining FGF10 (50 ng/mL) and KAAD-cyclopamine (1 μM) followed by 2more days that also contained DAPT (1 μM). Step 3 comprised 5 daysdifferentiation in CMRL with B27 supplement (1:100) containing FGF10 (50ng/mL), KAAD-cyclopamine (1 μM), DAPT (1 μM) and either with or withoutthe addition of retinoic acid (1 μM). The fourth step comprised 4 daysdifferentiation in CMRL with B27 supplement (1:100) containingnicotinamide (10 mM), exendin 4 (50 ng/mL), hepatocyte growth factor(HGF 25 ng/mL), and insulin-like growth factor (IGF)-1 (50 ng/mL).Duplicate samples were taken from each plate at multiple time points andgene expression was analyzed by real-time quantitative PCR.

This early foregut endoderm became further specified by application ofretinoic acid which promoted the production of the pancreatic hormoneproducing cells. Importantly, the pancreatic endocrine hormone insulinwas not expressed unless retinoic acid was applied (at a concentrationof about 0.1-5 μM) for at least about 1 day (see FIGS. 5A-H). Thisstrongly suggests that the dorsal pancreatic bud is dominant withrespect to production of insulin producing beta cells. This result is indirect contrast to the rat and mouse in which insulin and glucagon areexpressed in both the ventral and dorsal buds. This pancreatic endodermstage is marked by expression of PDX1, HB9 and HNF6/onecut 2 markers.

Example 6 Gamma Secretase Inhibition Promotes Efficient Induction ofEndocrine Progenitors and Hormone-Expressing Cells

Human embryonic stem cells were differentiated for 19 days via a 5-stepprotocol to achieve islet hormone-expressing cells. The first stepcomprised 5 days differentiation in activin A (100 ng/mL) to robustlyproduce DE (D'Amour, K., et al., Nature Biotechnology 23, 1534-1541,(2005)). Step 2 comprised 2 days differentiation in RPMI with 2% FBScontaining FGF10 (50 ng/mL) and KAAD-cyclopamine (0.5 μM). Step 3comprised 4 days differentiation in CMRL with B27 supplement (1:100)containing FGF10 (50 ng/mL), KAAD-cyclopamine (0.2 μM), and retinoicacid (1 μM). The fourth step comprised 2 days treatment with CMRL withB27 supplement (1:100) containing exendin 4 (40 ng/mL) and with varyingconcentrations of the gamma secretase inhibitor DAPT (0 μM, 1 μM, 3 μM,or 10 μM). The last step comprised 6 days differentiation in DMEM withB27 supplement (1:100) containing nicotinamide (10 mM), exendin 4 (40ng/mL), and insulin-like growth factor (IGF)-1 (50 ng/mL). Duplicatesamples were taken from each plate and gene expression was analyzed byreal-time quantitative PCR.

Following production of high levels of PDX1 protein in accordance withthe temporal application of factors and medium conditions describedabove, a final step to endocrine hormone production was addition of agamma secretase inhibitor. The gamma secretase inhibitor promoted thetransient induction of the transcription factor NGN3. It is known thatthe gamma secretase inhibitor efficiently blocks enzymatic release ofthe Notch intracellular domain, and thus, also functions as an inhibitorof Notch pathway activity (Notch inhibitor). Application of any of thestandard gamma secretase inhibitors in the range of their KD's resultsin Notch inhibition as measured by inhibition of expression of the Notchtarget genes such as HES1. As shown in FIGS. 6A-F, very little to noinsulin, glucagon, somatostatin or principal pancreatic transcriptionfactors were produced in the absence of DAPT. It is beneficial toprovide gamma secretase inhibition or Notch inhibition for a shortinterval after or during the retinoic acid differentiation step.

Example 7 Definitive Endoderm can be Differentiated Through a SequentialSeries of Steps in Order to Achieve Endocrine Hormone Expression

Human embryonic stem cells were differentiated for 16 days via either a4-step or 5-step protocol to achieve islet hormone-expressing cells. Thefirst step comprised 3 days differentiation in activin A (100 ng/mL) torobustly produce DE (D'Amour, K., et al., Nature Biotechnology 23,1534-1541, (2005)). Step 2 comprised 3 days differentiation in RPMI with2% FBS containing FGF10 (50 ng/mL) and KAAD-cyclopamine (0.2 μM). In the4-step protocol, step 3 comprised 4 days differentiation in CMRL withB27 supplement (1:100) containing FGF10 (50 ng/mL), KAAD-cyclopamine(0.2 μM), retinoic acid (2 μM), and DAPT (1 μM). In the 5-step protocol,this 4 day period was broken into two separate treatments in the samebase media. For 2 days the media contained FGF10 (50 ng/mL),KAAD-cyclopamine (0.2 μM), and retinoic acid (2 μM). During thesubsequent 2 days, the FGF10 was removed and the gamma-secretaseinhibitor DAPT (1 μM) was added. The last step of both protocolscomprised 6 days differentiation in DMEM with B27 supplement (1:100)containing nicotinamide (10 mM), exendin 4 (40 ng/mL), hepatocyte growthfactor (HGF 25 ng/mL), and insulin-like growth factor (IGF)-1 (50ng/mL). Duplicate samples were taken from each plate at multiple timepoints and gene expression was analyzed by real-time quantitative PCR.

As depicted in FIG. 1, there was a temporal continuum of gene expressionresulting in an invariant pattern of sequential transcription factorappearance leading to the production of pancreatic hormone producingcells. As shown in FIGS. 3A-L, the temporal dynamic of gene expressionindicated that the hESCs were transitioning through the sameintermediates that occur during development of the pancreas in vivo. Thefirst step of applying activin A in low FBS has been previouslycharacterized to robustly produce DE (D'Amour, K., et al., NatureBiotechnology 23, 1534-1541, (2005)). Following the formation of DE, theexpression of FOXA1 and HNF1b was significantly increased as a result ofthe treatment during step 2 (FIGS. 3A-B). This step (2-4 days in length)likely represent a posteriorization of the endoderm and was furtherpromoted by the removal of activin signaling. Furthermore, the additionof FGF10 (5-500 ng/ml) was beneficial together with the addition ofKAAD-cyclopamine (0.1-2 μM, sonic hedgehog inhibitor) which furtherspecified foregut cells into the pancreatic domain. The next step ofdifferentiation involved the application of retinoic acid (RA) andresulted in robustly increased expression of HNF6 and PDX1 (FIGS. 3C-D).To elicit further differentiation of PDX1-expressing pancreaticprogenitors down the endocrine lineage it was beneficial to inhibitNotch signaling. This was achieved by the application of an inhibitor ofgamma secretase. This class of drugs blocks the intramembrane cleavageof the Notch molecule, thereby precluding the release of the activatedNotch intracellular domain. A 2-4 day application of the gamma secretaseinhibitor DAPT, either in the terminal days of RA addition orimmediately following RA withdrawal, resulted in a transient inductionof NGN3 and PAX4 expression (FIGS. 3E-F). These two genes were expressedin endocrine progenitor cells but not mature endocrine hormone producingcells. The expression of the transcription factors NKX2.2 and NKX6.1 aswell as pancreatic hormones occurred subsequent to the induction of theendocrine precursor stage (FIGS. 3G-L).

Example 8 Pancreatic Endocrine Hormone Expression

Human embryonic stem cells were differentiated in this experiment asdescribed in Example 3 and Example 4 and then processed forimmunocytochemistry to detect islet antigens. Cultures were fixed for 15minutes at room temperature in 4% w/v paraformaldehyde in PBS, washedseveral times in TBS and blocked for 30 minutes in TBS++ (TBS containing3% normal donkey serum (Jackson ImmunoResearch Laboratories) and 0.25%w/v Triton X-100 (Sigma)). Primary and secondary antibodies (JacksonImmunoResearch Laboratories) were diluted in TBS++ and incubated for 24hours at 4° C. or 2 hours at room temperature, respectively.

As shown in FIGS. 7A-D, insulin, glucagon and somatostatin wereexpressed in individual cells within patches or isolated groups and alsoin cells expressing more than one hormone. As shown in FIGS. 8A-D,following the sequential differentiation from hESC to pancreatic islethormone-expressing cells, (ES/ME/DE/FE/PancE/PancEndocrine/Islethormone), individual insulin, glucagon and somatostatin cells wereproduced. In addition, as shown in panel 8D, double and triple labeledhormone containing cells were also produced. During early fetaldevelopment of the human pancreas, there is initially an abundance ofmultiple hormone producing cells, which segregate with time to singlehormone producing cells. In a typical cluster produced by the methodsdescribed herein, we observed both single, double and triple positivecells in a ratio of about 32% insulin, about 20% somatostatin, about 10%glucagon and about 38% double positive cells.

Example 9 C-Peptide/Insulin Release and Glucose StimulatedC-Peptide/Insulin Secretion (GSIS)

Human embryonic stem cells were differentiated as described in Example 3first for the production of DE and ultimately on to islet hormoneexpression. Cells were fed fresh media each day and a sample of themedia was collected from the plate after each successive day during step4 of the differentiation. The levels of C-peptide in these media sampleswere measured by ELISA (see FIGS. 9A-B).

Human embryonic stem cells were differentiated as described in Example4. On day 22 the media was changed to CMRL with 10% FBS containingexendin 4 (50 ng/mL) and exchanged every other day. On day 26, a glucosestimulation assay was performed as follows. The cells were placed intomedia containing 1.6 mM glucose (g50) for 2 hours after which a mediasample was collected. The media was replaced with fresh media containing16 mM glucose (g400) and allowed to incubate 2 hours more after whichmedia samples were collected. Duplicate samples were also taken fromeach plate and gene expression was analyzed by real-time quantitativePCR (see FIGS. 10A-B).

As proof of function pancreatic beta cells must synthesize, store andrelease mature insulin. Insulin is initially synthesized as proinsulinafter which it is folded via disulfide bonding. Within the golgi bodiesthe folded proinsulin molecule is specifically cleaved by prohormoneconvertase releasing the C “connecting”-peptide from the disulfidelinked A and B chains. The mature insulin is stored in crystalline form(complexed with Zn) together with the C-peptide and released in a 1:1molar ratio. Exposure to elevated glucose levels results inCa²⁺-mediated insulin and C-peptide release via granule fusion to theplasma membrane.

As shown in FIGS. 9A-B, 1 day after insulin message was robustlyexpressed by QPCR, C-peptide/insulin could be measured by ELISA. Thelevels of C-peptide increased with time in culture and plateaued justafter insulin mRNA plateaued. In FIGS. 10A-B, 14 different conditionswere evaluated for insulin production. Conditions 2-4 and 13 which hadmeasurable insulin gene expression by QPCR also had (glucose stimulatedinsulin secretion) GSIS. These data strongly support the contention thatbona fide GSIS is occurring in these cells and that these hESC-derivedpancreatic insulin cells are functional.

Example 10 Differentiation of Additional Human Embryonic Stem Cell Linesto Pancreatic Islet Hormone-Expressing Cells

Two additional human embryonic stem cell lines were differentiated for15 or 16 days via a 5-step protocol to achieve pancreatic islethormone-expressing cells. The first step comprised 3 daysdifferentiation with activin A (100 ng/ml) to robustly produce DE(D'Amour, K., et al., Nature Biotechnology 23, 1534-1541, (2005)). Step2 comprised 3 days differentiation in RPMI with 2% FBS containing FGF10(50 ng/mL) and KAAD-cyclopamine (0.5 μM). Step 3 comprised 3 daysdifferentiation in CMRL with B27 supplement (1:100) containing FGF10 (50ng/mL), KAAD-cyclopamine (0.5 μM), and retinoic acid (2 μM). Step 4comprised 3 days differentiation in DMEM (BG02) or CMRL (BG01) with B27supplement (1:100) containing DAPT (1 uM) and exendin 4 (40 ng/mL). Thefifth step comprised 4 days (BG02) or 5 days (BG01) differentiation inCMRL (BG02) or DMEM (BG01) with B27 supplement (1:100) containingexendin 4 (40 ng/mL). Duplicate samples were taken from each plate atmultiple time points and gene expression was analyzed by real-timequantitative PCR.

As shown in FIG. 11 the differentiation protocol produced very similartransitions through cellular intermediates en route to production ofinsulin-expressing islet cells. PDX1-positive pancreatic endoderm wasfirst induced by application of retinoic acid during stage 3 (day 9).Endocrine precursors expressing NGN3 were produced during step 4 as aresult of inhibiting Notch signaling peaking at day 12. Subsequently,the NGN3 levels dropped as these endocrine precursors furtherdifferentiated to hormone-expressing phenotypes as indicated by theincreases in insulin expression at days 12-16. This and similardifferentiation protocols have also been applied to hESC lines BG03,Cyt-25, and Cyt-49 ESC lines. While there were quantitative differencesbetween cell lines for the effectiveness of a given differentiationprotocol, all cell lines qualitatively exhibited the same cellulartransitions and ultimately yielded hormone-expressing cells.

Example 11 Comparison of Differentiation Conditions

We have identified a core set of differentiation conditions that may beminimally sufficient to produce pancreatic islet hormone-expressingcells from hESCs. In the simplest format, the differentiation methodcomprised applying a TGFβ growth factor to hESCs to induce thedifferentiation of definitive endoderm (D'Amour, K., et al., NatureBiotechnology 23, 1534-1541, (2005) followed by the activation ofretinoid signaling in the endoderm cells. In building on this core setof conditions, various other growth factors were added exogenously thatincreased the effectiveness of the differentiation at one or more stepsbetween the hESC and the insulin-expressing cells. Table 2 describes acore set of conditions (treatment #1) as well as various modificationsthat resulted in enhanced production of hormone-expressing islet cells.

Human embryonic stem cell lines were differentiated for 17 days via a5-step protocol to produce pancreatic islet hormone-expressing cells.The first step comprised 3 days differentiation with activin A (100ng/ml) to robustly produce DE (D'Amour, K., et al., Nature Biotechnology23, 1534-1541, (2005)). Step 2 comprised 3 days differentiation in RPMIwith 2% FBS containing one of the following: (a) 100 ng/mL activin A(treatment i), (b) no exogenous growth factors (treatment ii), or (c) 50ng/mL FGF10 and 0.5 μM KAAD-cyclopamine (treatments iii and iv). Step 3comprised 3 days differentiation in CMRL with B27 supplement (1:100)containing either (a) 2 μM retinoic acid (treatments i-iii) or (b) 2 μMretinoic acid and 0.5 μM KAAD-cyclopamine (treatment iv). Steps 4 and 5were the same for all conditions (treatments i-iv). Step 4 comprised 2days differentiation in CMRL with B27 supplement (1:100) containing 1 μMDAPT and 40 ng/mL exendin 4. Step 5 comprised 5 days differentiation inCMRL with B27 supplement (1:100) containing 40 ng/mL exendin 4.Duplicate samples were taken from each plate at multiple time points andgene expression was analyzed by real-time quantitative PCR.

The following table shows the relative expression levels of NGN3 at day12 as well as insulin and glucagon at day 17 when normalized to the mostminimal condition in this experiment (treatment i).

TABLE 2 Day 12 Day 17 Day17 NGN3 INSULIN GLUCAGON Treatment i 1.00 1.001.00 Treatment ii 1.45 2.03 0.56 Treatment ii 256 166 59 Treatment iv397 342 121

The removal of TGFB signaling during step 2 (treatment ii) resulted inmodest improvements in NGN3 and insulin expression and a slight decreasein glucagon expression. The addition of FGF10 and KAAD-cyclopamine inthe absence of activin A during step 2 resulted in significant increasesin the performance of endocrine differentiation. The furthermodification of maintaining KAAD-cyclopamine in the presence of retinoicacid during step 3 further increased the performance 2-fold relative totreatment iii where retinoic acid was used alone.

Human embryonic stem cell lines were also differentiated for 15 days viaa 6-step protocol to achieve islet hormone-expressing cells. The firststep comprised 3 days differentiation with either; i) activin A (100ng/ml) or ii) activin A (100 ng/ml) and Wnt3a (25 ng/mL) to robustlyproduce DE (D'Amour, K., et al., Nature Biotechnology 23, 1534-1541,(2005)). Step 2 comprised 3 days differentiation in RPMI with 2% FBScontaining FGF10 (50 ng/mL) and KAAD-cyclopamine (0.5 μM). Step 3comprised 2 days differentiation in CMRL with B27 supplement (1:100)containing FGF10 (50 ng/mL), KAAD-cyclopamine (0.5 μM) and retinoic acid(2 μM). Step 4 comprised 2 days differentiation in CMRL with B27supplement (1:100) containing retinoic acid (2 μM) and DAPT (1 μM). Step5 comprised 2 days differentiation in CMRL with B27 supplement (1:100)containing DAPT (1 μM) and exendin 4 (40 ng/mL). Step 6 comprised 3 daysdifferentiation in CMRL with B27 supplement (1:100) containing exendin 4(40 ng/mL). Duplicate samples were taken from each plate at multipletime points and gene expression was analyzed by real-time quantitativePCR.

Table 3 shows the relative expression levels of PDX1 at days 8 and 12,NGN3 at day 12 as well as insulin and glucagon at day 15 when normalizedto the condition without added Wnt3a.

TABLE 3 Day 8 Day 12 Day 12 Day 15 Day 15 PDX1 PDX1 NGN3 INSULINGLUCAGON Treatment i 1.00 1.00 1.00 1.00 1.00 Treatment ii 5.56 8.9111.09 15.02 32.66

These data demonstrate that addition of Wnt3a during the first stepresulted in marked enhancement of endocrine cell differentiation.

Example 12 Production and Characterization of Immature PancreaticHormone-Expressing Cells Derived from Human Embryonic Stem Cells

Human embryonic stem cells (hESCs) were differentiated for 25 days via a5-step protocol to achieve immature pancreatic islet hormone-expressingcells. The first step comprised 1 day differentiation in Wnt3a (25ng/ml) Activin A (100 ng/ml) in serum-free media, followed by 2 days inactivin A (100 ng/ml) in media supplemented with 0.2% FBS to robustlyproduce DE (D'Amour, K., et al., Nature Biotechnology 23, 1534-1541,(2005)). Step 2 comprised 3 days differentiation in DMEM with 2% FBScontaining FGF10 (50 ng/ml) and KAAD-cyclopamine (0.25 μM). Step 3comprised 2 days differentiation in DMEM with B27 supplement (1:100),with exogenously added KAAD-cyclopamine (0.2 μM), FGF10 (50 ng/ml), andretinoic acid (2 μM). The fourth step comprised 6 days treatment withDMEM with B27 supplement (1:100) with exogenously added KAAD-cyclopamine(0.2 μM) and FGF10 (50 ng/ml). Step 5 comprised 11 days treatment withDMEM with B27 supplement (1:100) containing exendin 4 (50 ng/ml) andglucagon-like peptide 1, amino acids 1-37 (50 ng/ml).

For the experimental data shown in FIGS. 16A and 16B, the hESC cellswere differentiated as described in Example 16.

To confirm the presence of human immature pancreatic islethormone-expressing cells in the 23-day-old cultures, the cells wereanalyzed by immunocytochemistry for the expression of NCAM, NKX2.2, INS,and PAX6. Briefly, cultures were fixed for 15 minutes at 24° C. in 4%w/v paraformaldehyde in PBS, washed several times in PBS and blocked for30 minutes in PBST (TBS/0.1% w/v Triton X-100 (Sigma)) containing 5%normal donkey serum (NDS, Jackson ImmunoResearch Laboratories). Thecells were then incubated with primary antibodies to NCAM, NKX2.2, INSand/or PAX6. The primary antibodies were diluted in PBST/5% NDS. Thecells were incubated with the primary antibodies were for 24 hours at 4°C. or 2 hours at 24° C. The cells were then washed and incubated withsecondary antibodies for 1 hour at 24° C. Cy3 and Cy5 conjugated donkeyantibodies against mouse rabbit, and guinea pig, as appropriate, wereused at 1:500 (Jackson ImmunoResearch Laboratories). Alexa-488 andAlexa-555 conjugated donkey antibodies against mouse, rat, rabbit,guinea pig, and goat (Molecular Probes) were used at 1:500.

As shown in FIGS. 12A-D, NCAM and NKX2.2 were co-expressed inhESC-derived immature pancreatic islet hormone-expressing cells. Thesedata suggest that the timing of NCAM correlates with the “delamination”of nascent endocrine cells from the epithelium.

FIGS. 13A-D and 14A-F show that NCAM, PAX6 and INS were co-expressed inhESC-derived cells treated to differentiate to immature pancreatic islethormone-expressing cells. These data demonstrate that NCAM is a goodmarker for hESC-derived immature pancreatic islet hormone-expressingcells.

FIGS. 16A-B demonstrate that MAFB was co-expressed with insulinexpressing cells in hESC-derived immature pancreatic islethormone-expressing cells. The cells shown in FIGS. 16A-B weredifferentiated using the differentiation protocol described in Example15, below, and processed for immunocytochemistry as above. FIGS. 16C-Dshow the same pattern of MAFB and INS expression in cells derived from13.5 week old human fetal pancreas.

Example 13 Expression of Synaptophysin by Pancreatic Hormone-ExpressingCells Derived from Human Embryonic Stem Cells

Synaptophysin (SYP) is a known marker for endocrine cells from in vivosources. (Protela-Gomez et al, 2004). To confirm the production ofendocrine cells from hESCs, hESCs were differentiated using thefollowing protocol and analyzed by immunocytochemistry for expression ofSYP and NKX2.2.

Human embryonic stem cells were differentiated for 18 days via a 6-stepprotocol to achieve pancreatic islet hormone-expressing cells. The firststep comprised 1 day differentiation in Wnt3a (25 ng/ml) Activin A (100ng/ml) in serum-free media, followed by 1 day in activin A (100 ng/ml)alone, in media supplemented with 0.2% FBS and 3 days in Activin A (100ng/ml) in media supplemented with 2.0% FBS to robustly produce DE(D'Amour, K., et al., Nature Biotechnology 23, 1534-1541, (2005)). Step2 comprised 3 days differentiation in DMEM with 2% FBS containing FGF10(50 ng/ml) and KAAD-cyclopamine (0.25 μM). Step 3 comprised 1 daydifferentiation in DMEM with B27 supplement (1:100) and retinoic acid (1μM). The fourth step comprised 6 days treatment with DMEM with B27supplement (1:100) with exogenously added KAAD-cyclopamine (0.2 μM) andFGF10 (50 ng/ml) and retinoic acid (1 μM). Step 5 comprised 1 daytreatment with DMEM with B27 supplement (1:100) containing FGF10 (50ng/ml) and KAAD-cyclopamine (0.25 μM). Step 6 comprised 4 days treatmentwith DMEM with B27 supplement (1:100) and exendin 4 (50 ng/ml).

The cells were fixed and processed as described above, using anti-SYP,anti-NKX2.2 primary antibodies. FIGS. 15A-B show the co-expression ofSYP and NKX2.2, confirming the production of immature pancreatic islethormone-expressing cells.

Example 14 Analysis of NCAM-Labeled hESC-Derived Immature PancreaticHormone-Expressing Cells Using Flow Cytometry

Human embryonic stem cells (hESCs) were differentiated for 18 days via a5-step protocol to achieve immature pancreatic islet hormone-expressingcells. The first step comprised 1 day differentiation in Wnt3a (25ng/ml) activin A (100 ng/ml) in serum-free media, followed by 1 day inactivin A (100 ng/ml) in media supplemented with 0.2% FBS and 1 day inactivin A (100 ng/ml) in media supplemented with 2.0% FBS to robustlyproduce DE (D'Amour, K., et al., Nature Biotechnology 23, 1534-1541,(2005)). Step 2 comprised 3 days differentiation in DMEM with 2% FBScontaining FGF10 (50 ng/ml) and KAAD-cyclopamine (0.25 μM). Step 3comprised 4 days differentiation in DMEM with B27 supplement (1:100),with exogenously added KAAD-cyclopamine (0.2 μM), and retinoic acid (2μM). The fourth step comprised 3 days treatment with DMEM with B27supplement (1:100) with exogenously added KAAD-cyclopamine (0.2 μM) andexendin 4 (50 ng/ml). Step 5 comprised 5 days treatment with DMEM withB27 supplement (1:100) containing exendin 4 (50 ng/ml).

Single cell suspensions of hESC-derived cells treated as described abovewere obtained as follows: Cell cultures were dissociated with eitherTRYPLET (Invitrogen, Catalog. No. 12563-011) or ACCUTASE enzymes(Innovative Cell Technologies, Catalog No. AT104) at 37° C. according tothe manufacturer's instructions. The cells were then washed with PBS/10%FBS collected by centrifugation and resuspended in PBS/3% FBS. Cellswere incubated with anti-NCAM antibody directly conjugated to PE for 20minutes on ice and then washed. Intracellular antibody staining wasperformed by treating the NCAM-PE stained cells from above withCYTOFIX/CYTOPERM fixation and permeability buffer and PERM/WASH washbuffer (Beckton Dickinson) according to the manufacturer's instructions.Cells were incubated anti-insulin (DakoCytomation, Catalog No. A0564),and anti-synaptophysin (DakoCytomation, Catalog No. A0010) primaryantibodies for 20 minutes on ice. Cells were washed and incubated witheither donkey anti-guinea pig Cy5 1:1000 (Jackson Immunoresearch706-176-148), donkey anti-rabbit Alexa 488 1:2000 (Invitrogen A21206)secondary antibodies according to the manufacturer's instructions.

Flow cytometry was performed on a FACSARIA Fluorescence activated cellsorter (Becton Dickinson), according to the manufacturer's instructionsand analyzed using FACSDIVA FACS analysis software (Becton Dickinson).

As shown in FIG. 17A, approximately 10% of the hESC-derived cellsdifferentiated as described were SYP positive. Moreover, almost all ofthe SYP positive hESC-derived cells were also positive for NCAM. FIG.17B shows that almost all of the NCAM positive hESC-derived cells werealso positive for INS. These data confirm the immunocytochemistry datain FIGS. 12-16, and demonstrate that NCAM is a useful marker forhESC-derived immature pancreatic islet hormone-expressing cells.

Example 15 Sorting NCAM Positive hESC-Derived Immature Pancreatic IsletHormone-Expressing Cell Populations Enriches the Populations forImmature Pancreatic Islet Hormone-Expressing Cells

In a second set of experiments, hESCs were differentiated for 19 daysvia a 6-step protocol to achieve immature pancreatic islethormone-expressing cells. The first step comprised 1 day differentiationin Wnt3a (25 ng/ml) activin A (100 ng/ml) in serum-free media, followedby 1 day in activin A (100 ng/ml) alone in media supplemented with 0.2%FBS, and 1 day in activin A (100 ng/ml) in media supplemented with 2.0%FBS to robustly produce DE (D'Amour, K., et al., Nature Biotechnology23, 1534-1541, (2005)). Step 2 comprised 3 days differentiation in DMEMwith 2% FBS containing FGF10 (50 ng/mL) and KAAD-cyclopamine (0.25 μM).Step 3 comprised 4 days differentiation in DMEM with B27 supplement(1:100), with exogenously added KAAD-cyclopamine (0.2 μM), and retinoicacid (2 μM). The fourth step comprised 1 day treatment with DMEM withB27 supplement (1:100) with exogenously added KAAD-cyclopamine (0.2 μM)and glucagon-like peptide 1, amino acid 1-37 (50 ng/ml). Step 5comprised 3 days treatment with DMEM with B27 supplement (1:100) withexogenously added exendin 4 (50 ng/mL) and glucagon-like peptide 1,amino acids 1-37 (50 ng/ml). Step 6 comprised 5 days treatment with DMEMwith B27 supplement (1:100) containing exendin 4 (50 ng/ml).

Differentiation protocols were modified as follows for particularexperiments. For the experimental data shown in FIG. 19, Step 3 of theprotocol above included treatment with noggin (100 ng/ml). In Step 4,instead of treatment with glucagon-like peptide 1, cells were treatedwith exendin 4 (50 ng/ml) Step 5 comprised a 5 day treatment that didnot include glucagon-like peptide 1. Finally, Step 6 was replaced by a4-day treatment in CMRL media with B27 supplement (1:100) containingexendin 4 (50 ng/ml).

For the experimental data shown in FIG. 20, Step 3 was modified to a 3day treatment that included noggin (100 ng/ml). Step 4 was modified toinclude nicotinamide (10 mM). Step 5 was modified to a 4 day treatmentthat included nicotinamed (10 mM), and that did not include exendin 4.Step 6 was modified to comprise a 1 day treatment that includedglucagon-like peptide 1, 1-37 (50 ng/ml) and nicotinamide 10 mM. Thecell differentiation protocol also included a seventh step, comprising 4days treatment in CMRL media with B27 supplement (1:100), glucagon-likepeptide 1, 1-37 (50 ng/ml) and nicotinamide (10 mM).

For the experimental data shown in FIG. 25, Step 3 of thedifferentiation protocol was modified to include treatment with retinoicacid at 1 μM, and included treatment with noggin (50 ng/ml) andnicotinamide (10 mM). Step 4 was modified to include nicotinamide (10mM) and to exclude treatment with glucagon-like peptide 1, 1-37. Stepwas modified to include nicotinamide (10 mM) and to exclude treatmentwith glucagon-like peptide 1, 1-37, and exclude exendin 4. Step 6 wasmodified to only be a 1 day treatment and excluded exendin 4. The celldifferentiation also included a seventh step, comprising 7 daystreatment in CMRL supplemented with B27 (1:100).

Single cell suspensions of the cells were obtained as described above.The cells were then washed with PBS/10% FBS collected by centrifugationand resuspended in PBS/3% FBS. Cells were incubated with anti-NCAMdirectly conjugated to PE (NCAM16.2, Becton Dickinson, Catalog No.340363) for 20 minutes on ice. Cells were subsequently washed withPBS/3% FBS collected by centrifugation and resuspended in Hanks balancedsalt solution, 2% FBS, 20 mM HEPES. Cells were sorted with a FACS Ariamachine (Becton Dickinson), and collected in Hanks balanced saltsolution with 10% FBS. Intracellular antibody staining was performed bytreating either the pre-sorted population of cells or the NCAM-positivesorted population of cells with CYTOFIX/CYTOPERM fixation andpermeability buffer and PERM/WASHwash buffer (Beckton Dickinson)according to the manufacturer's instructions. Cells were washed andincubated with either donkey anti-guinea pig Cy5 1:1000 (JacksonImmunoresearch 706-176-148), donkey anti-rabbit Alexa 488 1:2000(Invitrogen A21206) secondary antibodies according to the manufacturer'sinstructions.

Flow cytometry was performed on a FACSARIA Fluorescence activated cellsorter (Becton Dickinson), according to the manufacturer's instructionsand analyzed using FACSDIVA FACS analysis software (Becton Dickinson).

NCAM positive and NCAM negative cells were collected and then reanalyzedby flow cytometry using the protocol above for NCAM, SYP, PAX6 and CHGA.In one experiment, following sorting (shown in FIG. 18A), NCAM positivecells were aggregated in inverted hanging drops. These cells werecollected and analyzed in cryosections using immunocytochemistry forPAX6, INS, and GCG. Approximately 7,000 NCAM positive sorted cells wereseeded per drop, cultured in RPMI media containing 10% FBS, Fibronectin,Laminin, Collagen, HGF and EGF and incubated for 72 hours. The cellaggregates were collected and processed for immunocytochemical analysisas described above.

As shown in FIG. 18B, when cells were analyzed by flow cytometry priorto sorting for NCAM, approximately 7% of the cell population was bothNCAM positive and SYP positive. Sorting NCAM positive cells (FIG. 18A,“left sort”) resulted in an approximately 4-fold enrichment for NCAMpositive/SYP positive cells compared to cells that were not sorted (FIG.18B). As shown in FIG. 18D, the population of NCAM negative cells wasdepleted for SYP positive cells. FIGS. 19A and 19D show that anhESC-derived cell population differentiated as described above andanalyzed by flow cytometry for NCAM comprised approximately 4% and 2%NCAM positive/SYP positive and NCAM positive/INS positive cells. FIG.19B shows that sorting the same population of NCAM positive hESC-derivedcells resulted in a greater than 10-fold enrichment of NCAM positive/SYPpositive cells, producing a cell population comprising 47% NCAMpositive/SYP positive cells. FIG. 19D shows that sorting the samepopulation of hESC-derived cells resulted in a greater than 8-foldenrichment of NCAM positive/INS positive cells. As shown in FIGS. 20A-C,sorting NCAM positive hESC-derived cells differentiated as describedabove produced an enriched cell population that comprised 72% NCAMpositive/SYP positive cells.

FIGS. 25A-F show the results of an independent experiment. As shown inFIG. 25, NCAM positive/SYP positive cells represented about 7.4% of thecell population prior to sorting. Sorting of NCAM positive cellsresulted in a population that is about 42% SYP positive, a greater than5-fold enrichment (25A-B). Similarly, sorting of NCAM positive cellsenriched the cell population for CHGA-expressing cells from about 8.7%of the cell population to about 42% of the cell population (25C-D).Likewise, the NCAM sorting enriched the cell population forINS-expressing cells from about 6% of the total cell population to about24% of the cell population (25E-F).

FIGS. 27A-D and 28A-D show that hanging drop aggregates of NCAM positivesorted cells contained a significant proportion of cells thatco-expressed PAX6 and INS. FIGS. 28A-D show that NCAM positive sortedcells contained a significant proportion of cells that co-expressed GCGand INS.

The data demonstrate that NCAM is useful for sorting cells using FACS.As such, NCAM can be used to enrich, isolate and/or purify hESC-derivedimmature pancreatic hormone-expressing cells.

Example 16 Enrichment of NCAM Positive/SYP Positive hESC-DerivedImmature Pancreatic Islet Hormone-Expressing Cell Populations Using aNegative Selection for CD133

In a third set of experiments, hESCs were differentiated for 19 days viaa 6-step protocol to achieve immature pancreatic islethormone-expressing cells. The first step comprised 1 day differentiationin Wnt3a (25 ng/ml) activin A (100 ng/ml) in serum-free media, followedby 1 day in activin A (100 ng/ml) alone in media supplemented with 0.2%FBS, and 1 day in activin A (100 ng/ml) in media supplemented with 2.0%FBS to robustly produce DE (D'Amour, K., et al., Nature Biotechnology23, 1534-1541, (2005)). Step 2 comprised 3 days differentiation in DMEMwith 2% FBS containing FGF10 (50 ng/mL) and KAAD-cyclopamine (0.25 μM).Step 3 comprised 3 days differentiation in DMEM with B27 supplement(1:100), with exogenously added KAAD-cyclopamine (0.2 μM), retinoic acid(2 μM), and exendin 4 (50 ng/ml). The fourth step comprised 1 daytreatment with DMEM with B27 supplement (1:100) with exogenously addedKAAD-cyclopamine (0.2 μM) and exendin 4 (50 ng/ml). Step 5 comprised 9days treatment with DMEM with B27 supplement (1:100) containing exendin4 (50 ng/ml).

Cell cultures were processed for flow cytometry analysis as describedabove, using NCAM, SYP and CD133 primary antibodies as described inExample 14, or sorted using NCAM and CD133 antibodies as described inExample 15.

As shown in FIG. 21B, approximately 7.5% of the cells in thehESC-derived cell population differentiated as described in Example 14were NCAM positive/CD133 negative. Counterstaining of these cells forSYP, showed that 93% of the NCAM positive/CD133 negative cells werepositive for SYP.

As shown in FIGS. 26A and 26B, approximately 4.6% of the cell populationdifferentiated as described above stained positively for SYP, andapproximately 5.3% of the cell population stained positively for NCAMand negative for CD133. By contrast, approximately 66.5% of thesubpopulation of NCAM positive/CD133 negative cells stained positivelyfor SYP (26C). These data demonstrate that sorting for NCAM positive andCD133 negative cells can be used to enrich, isolate and/or purifyhESC-derived immature pancreatic hormone-expressing cells.

Example 17 Differentiation of hESCs to Endocrine Precursor Cells andImmature Pancreatic Islet Hormone-Expressing Cells

hESCs were differentiated for 19 days via a 6-step protocol to achieveimmature pancreatic islet hormone-expressing cells. The first stepcomprised 1 day differentiation in Wnt3a (25 ng/ml) activin A (100ng/ml) in serum-free media, followed by 1 day in activin A (100 ng/ml)alone in media supplemented with 0.2% FBS, and 1 day in activin A (100ng/ml) in media supplemented with 2.0% FBS to robustly produce DE(D'Amour, K., et al., Nature Biotechnology 23, 1534-1541, (2005)). Step2 comprised 3 days differentiation in DMEM with 2% FBS containing FGF10(50 ng/mL) and KAAD-cyclopamine (0.25 μM). Step 3 comprised 4 daysdifferentiation in DMEM with B27 supplement (1:100), with exogenouslyadded KAAD-cyclopamine (0.2 μM), retinoic acid (2 μM), glucagon-likepeptide 1, amino acid 1-37 (50 ng/ml), and NOGGIN (50 ng/ml). The fourthstep comprised a 3 day treatment with DMEM with B27 supplement (1:100)and glucagon-like peptide 1, amino acid 1-37 (50 ng/ml). Step 5comprised 6 days treatment with DMEM with B27 supplement (1:100)containing exendin 4 (50 ng/ml). On days 12, 15 and 1919, cells weresorted using FACS as described in Example 14 to separate NCAM positivecells from NCAM negative cells. Duplicate samples of pre-sorted cells,NCAM positive cells and NCAM negative cells were taken from each cultureand gene expression was analyzed by real-time quantitative PCR.

As shown in FIG. 22, there was a temporal continuum of gene expressionas cells progressed from endocrine precursor cells (“early”) to immaturepancreatic islet hormone-expressing cells (“middle” and “late”). FIGS.22A and 22B show that NCAM positive cells were enriched for NGN3 andPAX4. The expression of NGN3 and PAX4 decreased as the hESCsdifferentiated into immature pancreatic islet hormone-expressing cells.As shown in FIGS. 22C-K, NCAM-positive cells were also highly enrichedfor cells expressing markers indicative of immature pancreatic islethormone-expressing cells, including INS, PP, PAX6, GCG, GHRL, GCK, SST,NKX2.2, and SYP, compared to NCAM negative cells. Endocrine precursorcells did not substantially express INS, PP, PAX6, GCG, GHRL, GCK, andSYP, whereas cells that were further differentiated towards pancreaticislet hormone-expressing cells exhibited increased expression of thesame markers, which are characteristic of pancreatic endocrine cells.

FIGS. 23A-E show additional QPCR data hESC cells that weredifferentiated and sorted on day 19 as described above. Sorting thehESC-derived cell population for NCAM positive cells produced apopulation of cells that was highly enriched for endocrine markers suchas NEUROD (23A), ISL1 (23B), GAS (23C), KIR6.2 (23D), and SUR1 (23E).

FIGS. 24A-K represent an independent experiment performed onhESC-derived cells that were differentiated and sorted on day 19 asdescribed above. In this experiment, data labeled “Pre-sort” wasobtained from hESC differentiated as described above that had beengated, but not sorted using FACS. The figures show that sorting the cellpopulation for NCAM produces a population of cells that was highlyenriched for NCAM (24A), as expected, as well as the following markersthat are characteristic of endocrine cells: NKX2.2 (24B), SYP (24C),PAX6 (24D), NEUROD (24E), ISL1 (24F), INS (24G), GCG (24H), GHRL (24I),SST (24J), and PP (24K). These data confirm that NCAM is useful for theenrichment, isolation and purification of immature endocrine cells.

Example 18 Method of Obtaining Insulin-Expressing Cells Using withoutExogenous Retinoids

This example demonstrates an alternative method for differentiatinghESCs to insulin-expressing cells using noggin treatment without theaddition of an exogenous retinoid source, for example retinol (vitaminA) which may be present in media supplements such as B27.

Human ESCs were differentiated to definitive endoderm cells viatreatment with activin A (100 ng/ml) and Wnt3a (25 ng/ml) in RPMI+0% FBSfor the first day and then for 2 more days with activin A (100 ng/ml)alone in RPMI+0.2% v/v FBS. Definitive endoderm was differentiated toforegut endoderm by treatment with KGF (50 ng/ml) and KAAD-cyclopamine(0.25 μM) for 3 days in RPMI+2% v/v FBS. Differentiation then proceededin DMEM+1% v/v B27 supplement containing KGF (50 ng/ml) andKAAD-cyclopamine (0.25 μM) for one day followed by 5 additional days ofthe same with or without the addition of noggin (100 ng/ml). The B27supplement used was either with (B27+) or without (B27−) vitamin A. Ondays 13, 14 and 15 of differentiation, the KGF was removed but theKAAD-cyclopamine (0.25 μM) and noggin (when used) remained in theculture medium. The differentiation medium for days 16-19 consisted ofCMRL+1% v/v B27 (with or without vitamin A as in previous conditions)with no additional factors. Cultures were sampled in duplicate on days3, 6, 9, 12, 15 and 19 of differentiation and analyzed for expression ofpancreatic markers using real-time PCR.

Induction of PDX1 gene expression was not dependent on either noggintreatment or the presence or absence of vitamin A in the B27 supplement(FIG. 29A). In contrast, the induction of pancreatic endocrinedifferentiation, as evidenced by NGN3 expression induced at day 12, washighly dependent on the presence of noggin (FIG. 29B). Subsequent to theinduction of NGN3 expression, the expression of pancreatic hormones INS,GCG, SST, and GHRL was also dependent on the presence of noggin (FIGS.29C-F). The ability for noggin to maintain NGN3 expression beyond day 12was enhanced by the presence of vitamin A in the B27 supplement. Inaddition, the magnitude of pancreatic hormone expression was alsoenhanced by the presence of vitamin A in the B27 supplement, however, inthe complete absence of exogenous retinoid application noggin treatmentwas still sufficient to induce differentiation to insulin-expressingcells.

Example 19 Method of Obtaining Insulin-Expressing Cells UsingCombination of Noggin and Retinoic Acid

This example demonstrates that noggin and retinoic acid can be used inconjunction for differentiating hESCs to insulin-expressing cells andthat the addition of noggin to retinoic acid potentiates the action ofthe retinoic acid, particularly when retinoic acid is used at lowerconcentrations.

Human ESCs were differentiated to definitive endoderm via treatment withactivin A (100 ng/ml) and Wnt3a (25 ng/ml) in RPMI+0% FBS for the firstday and then for 2 more days with activin A (100 ng/ml) alone inRPMI+0.2% v/v FBS. Definitive endoderm was differentiated to foregutendoderm by treatment with KGF (50 ng/ml) and KAAD-cyclopamine (0.25 μM)for 3 days in RPMI+2% v/v FBS. Differentiation then proceeded for 3 daysin DMEM+1% v/v B27 supplement containing KAAD-cyclopamine (0.25 μM) andall-trans retinoic acid (0.1 μM or 2 μM) with or without the addition ofnoggin (0, 30 or 100 ng/ml). This was followed by a 2 day treatmentperiod with the gamma-secretase inhibitor RAPT (1 μM) provided inDMEM+1% v/v B27 and subsequently the cells were cultured in CMRL+1% v/vB27 with no additional growth factors.

The concentration of retinoic acid and the addition of noggin had verylittle effect on the expression levels of PDX1 at days 9 or 11 (FIG.30A). However, the addition of noggin to low dose RA (0.1 μM)dramatically enhanced the expression of the endocrine progenitor markerNGN3 at day 9 (FIG. 30B) as well as the initial appearance of INS andGCG gene expression at day 11 (FIGS. 30E and 30F). This result may bedue to an enhancement of differentiation to pancreatic epithelium asindicated by the enhanced expression of PTF1A (FIG. 30C) and NKX6-1(FIG. 30D), particularly in condition “C” using lower RA concentration(0.1 μM) and high noggin concentration (100 ng/ml). These resultsdemonstrated that the combination of noggin and retinoid signaling actssynergistically to specify pancreatic epithelium and ultimatelypancreatic endocrine differentiation from foregut endoderm derived fromhESCs.

Example 20 In Vivo Maturation of Pancreatic Epithelium

In order to further study the potential of hESC-derived material tofurther differentiate into functional insulin-producing cells, wetransplanted in vitro differentiated cells into immunocompromised mice(SCID/Bg). To achieve this, confluent cells at various stages of thedifferentiation process were mechanically scored using a modifiedMcIlwain tissue chopper (see Joannides et al., (2006). Stem Cells24:230-235, the disclosure of which is incorporated herein by referencein its entirety) and subsequently transferred to nonadherent plates forculture. The resultant aggregates were pipetted onto gelatin spongescaffolds (Gelfoam; Pharmacia) and overlaid with Matrigel (BD). Each 8mm diameter×2 mm scaffold was loaded with 25-40 μl of aggregates. Two ofthese tissue constructs were subsequently transplanted into theepididymal fat pad of each mouse.

Grafted material was allowed to differentiate and mature in vivo. Everytwo weeks, functionality of the insulin-producing cells in these graftswas tested by injecting animals with arginine to induce insulinsecretion. Blood was collected 4 minutes after arginine injection andtested for human C-peptide. Human C-peptide was detected in animal serumas early as 5 weeks after transplantation and increased over time. Tento sixteen weeks post-transplant, two animals contained grafts that wereresponsive to glucose. These data suggest that the number of functionalinsulin-producing cells in the grafts is increasing over time probablythrough a combination of progenitor proliferation and maturation.

Histological examination of grafts harvested at different time pointsrevealed the presence of expanding and maturing pancreatic epithelium.Grafts harvested at later time points had larger amounts of thisepithelium. Pancreatic epithelium was identified by morphology andexpression of typical developmental markers such as Pdx1 and Nkx6.1.Examination of hormone markers revealed that islet-like cell clustersbudded off of the pancreatic epithelium in a manner analogous to normalpancreatic development. These clusters contained singly-positivehormonal cells including insulin-cells that are also Nkx6.1-positive andPdx1-positive. The cell cluster architecture resembled that of normalfetal islets.

The methods, compositions, and devices described herein are presentlyrepresentative of preferred embodiments and are exemplary and are notintended as limitations on the scope of the invention. Changes thereinand other uses will occur to those skilled in the art which areencompassed within the spirit of the invention and are defined by thescope of the disclosure. Accordingly, it will be apparent to one skilledin the art that varying substitutions and modifications may be made tothe invention disclosed herein without departing from the scope andspirit of the invention.

As used in the claims below and throughout this disclosure, by thephrase “consisting essentially of” is meant including any elementslisted after the phrase, and limited to other elements that do notinterfere with or contribute to the activity or action specified in thedisclosure for the listed elements. Thus, the phrase “consistingessentially of” indicates that the listed elements are required ormandatory, but that other elements are optional and may or may not bepresent depending upon whether or not they affect the activity or actionof the listed elements.

REFERENCES

Numerous literature and patent references have been cited in the presentpatent application. Each and every reference that is cited in thispatent application is incorporated by reference herein in its entirety.

For some references, the complete citation is in the body of the text.For other references the citation in the body of the text is by authorand year, the complete citation being as follows:

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What is claimed is:
 1. A first and second cell population comprising: a) a first in vitro cell population comprising human pluripotent cells; and b) a second in vitro cell population comprising progeny of a portion of the first cell population, wherein the progeny comprise at least 5% endocrine precursor cells that express a marker selected from the group consisting of neurogenin 3 (NEUROG3), paired box 4 (PAX4) and NKX2 transcription factor related locus 2 (NKX2.2).
 2. The first and second cell population of claim 1, wherein said endocrine precursor cells are multipotent cells that can differentiate into pancreatic islet hormone-expressing cells that express at least one pancreatic hormone selected from the group consisting of insulin, somatostatin, ghrelin, pancreatic polypeptide and glucagon.
 3. The first and second cell population of claim 1, wherein said endocrine precursor cells express NEUROG3, PAX4 and NKX2.2.
 4. The first and second cell population of claim 1, wherein the progeny comprise at least 50% endocrine precursor cells.
 5. The first and second cell population of claim 1, wherein said endocrine precursor cells do not substantially express a pancreatic hormone selected from the group consisting of ghrelin, insulin, somatostatin and glucagon.
 6. The first and second cell population of claim 1, wherein said endocrine precursor cells are non-recombinant cells.
 7. The first and second cell population of claim 1, wherein said endocrine precursor cells express NCAM.
 8. The first and second cell population of claim 1, wherein said endocrine precursor cells comprise a reagent bound to NCAM.
 9. The in vitro cell culture of claim 8, wherein said reagent comprises a molecule selected from the group consisting of an anti-NCAM antibody, an anti-NCAM antibody fragment and an NCAM ligand.
 10. The first and second cell population of claim 9, wherein said reagent is an anti-NCAM antibody.
 11. The first and second cell population of claim 10, wherein said anti-NCAM antibody is labeled.
 12. The first and second cell population of claim 1, wherein said first in vitro cell population comprises at least 10% human pancreatic duodenal homeobox 1 (PDX1)-positive pancreatic endoderm cells.
 13. The first and second cell population of claim 1, wherein said first in vitro cell population comprises at least 50% human pancreatic duodenal homeobox 1 (PDX1)-positive pancreatic endoderm cells.
 14. The first and second cell population of claim 1, wherein the first in vitro cell population further medium-comprises a factor selected from retinoic acid (RA) and exendin 4 (Ex4).
 15. A first and second cell population comprising a) a first in vitro cell population comprising human pluripotent cells; and b) a second in vitro cell population comprising progeny of a portion of the first cell population, wherein the progeny are obtained by: (1) providing said first in vitro cell population with a TGFβ superfamily growth factor; (2) withdrawing the TGFβ superfamily growth factor from said cell population; (3) providing said cell population with a retinoid; and (4) incubating said cell population in a culture medium for a sufficient time to permit formation of human endocrine precursor cells expressing a marker selected from the group consisting of neurogenin 3 (NEUROG3), paired box 4 (PAX4) and NKX2 transcription factor related locus 2 (NKX2.2).
 16. The first and second cell population of claim 15, wherein step (2) further comprises providing said cell population with FGF.
 17. The first and second cell population of claim 15, wherein said retinoid comprises retinoic acid.
 18. The first and second cell population of claim 15, wherein step (4) further comprises providing said cell population with a gamma secretase inhibitor. 